IDC has evolved over time, and each build release has added new functionality and features (and fixed bugs). Version 1.1 represents significant additions that may change several aspects of the game, especially at higher levels (20+). The core essence of the game has remained the same, but it is useful to point out the changes here on one page so that players that have played prior to 1.1 can see everything in one place. The specific sections of the Guide will be updated in the near future.
ABILITY UPGRADES: Most (not all) abilities can now be upgraded at some point. This process is called 
FACTORING (e.g., Factor II, Factor III, and Factor IV). Abilities that are upgraded display the roman numeral over their icon as seen here. Upgraded abilities are more powerful but use more stamina. Abilities that factor can be upgraded every 10 levels beyond their MINIMUM LEVEL. For example, the Ranger and Rogue’s FLAMING ARROW ability is level 1. It can be upgraded to Factor II at level 11, Factor III at level 21, and Factor IV at level 31.
Upgrading abilities costs progressively more ABILITY POINTS (which are awarded when you level up). Upgrading an ability from its original form to Factor II costs 2 ability points. To Factor III costs 4 ability points. And to Factor IV costs 6 ability points.
Generally, when you upgrade an ability’s factor, the stamina cost rises by 50% and the DURATION and COOLDOWN each increase by 1. However, the effects of each ability generally increase too. PHYSICAL and ELEMENTAL DAMAGE usually doubles. The chance for any given STATUS EFFECT increases by 15% (so a 40% STUN rate becomes 46%). RESISTANCES rise by 15% (e.g., 40% FIRE RESISTANCE becomes 46%). Summoned creatures’ levels increase by 10. Those are generalities, and different abilities can vary, so you’ll need to refer to the specific ability when upgrading to see specifics.
There are still quite a few abilities that cannot be upgraded (you’ll see this icon 
). Typically, these are weapon-based abilities where the damage or the effect is dependent on the weapon itself (e.g., POWER ATTACK, PRECISION STRIKE, SWEEP ATTACK, COUNTER ATTACK). These don’t upgrade because the assumption is that as you level up and get better weapons, they are naturally upgrading along the way.
Some abilities don’t factor, but have explicit upgrades. An example of this is the Mage and Druid’s OPEN SIMPLE LOCK, OPEN MODERATE LOCK, and OPEN HARD LOCK abilities. Each of these requires the one below before you can add it when leveling up, but the older one still exists in your abilities list and either can be used. And these only cost one ability point to acquire each new ability.
When you look at the description for any given ability, information on whether it can be upgraded or not will be given including at what level it can be upgraded.
By the way … monsters get factor upgrades as well. You won’t know who has what, but you should feel it when they attack. Fair is fair. You really won’t see this prior to level 20 or so, but at level 30 you should expect most monsters to have about one or two of their abilities upgraded to at least Factor II. At level 40, likely three or four at Factor II or even one at Factor III. You probably won’t see a Factor IV until level 75+. The GAME DIFFICULTY will affect this. A higher setting will translate to more ability upgrades on monsters.
Important note regarding upgrading: Just because you CAN upgrade an ability doesn’t mean you SHOULD. You have to take into consideration the stamina cost of using the new ability as well as the ability points cost. For example, it doesn’t make much sense to upgrade an ability as soon as you possibly can at level 11 if its stamina cost is a quarter or more of your total stamina. You couldn’t use it very often (something like a summon may be an exception to this). Unless you really like that ability and use it a lot and the upgrade effects are significant. The reality is that most players shouldn’t even think about upgrading anything until maybe level 20. And even at that, maybe only a select few. You don’t need to upgrade everything. And it’s possible that acquiring two new abilities would be better than upgrading one.
ABILITY STAMINA COST: Due to the changes mentioned above related to upgrading abilities, the formula for the stamina cost to use an ability has changed. Previously, as you rose in level above the MINIMUM LEVEL of the ability, the stamina cost would go down. At about 10 levels above each ability’s minimum level, the stamina cost would be roughly half of what it was if you were the same level as the minimum level and then stay there from that point on. The thinking was that as you progressed, each ability got “easier” and therefore used less stamina. This has been removed, and the stamina cost for any given ability is now static no matter what level you are. So if you’re a level 10 Mage casting PRISMATIC LIGHTS, which is a level 3 spell, it costs the same amount of stamina as if you were a level 3 Mage. With the addition of ability upgrades, this system no longer made sense as there would be an outsized jump in stamina cost before and after you upgraded.
QUESTS: Many users have been asking for quests for a long time, and I’ve finally put them in (with the ability to add more over time). These are technically referred to as JOBS and they are listed on the JOBS BULLETIN BOARD outside the Mayor’s Office as well as inside by clicking the JOBS button. However, these differ from the old-style jobs (which are still in there) as they usually require you to go through The Gate and retrieve certain items or kill certain creatures to get the reward. They are much harder than the existing jobs and involve a full party, not just one person (but you can go solo if you want). Many of them offer significant rewards (such as magikal items), good coin, and XP.
Most of these “quests” give you several months to complete, and you can choose which worlds to journey to in order to complete them (for example, there is one that requires you to return with 2 giant hearts, but giants can be found in multiple worlds). Some of these can only be accomplished in a given world and must be undertaken right away, and once you accept them and go to The Gate only that world will be enabled. Some of these are multi-part and include taking out “bosses”, and you must complete a series of them before you can get to the final stage. And they’re all optional. If you just want to dungeon-dive, have at it! But you should check the bulletin board to see what is available. Like other jobs, most of these come and go and are only available for a limited time. There are currently about 30 of these that have been added (with plans to add more), so they provide a good variety.
On the world screen’s top HUD bar there is now a 
JOBS button that appears when you have an active quest. Hovering over this gives a quick review of your quest’s goal and clicking it will display more information.
USER INTERFACE IMPROVEMENTS (PC VERSION): This version includes many quality-of-life improvements, including being able to control vertical scrollbars and the screen zoom level in combat using the mouse wheel. You can also control the map zoom level with the mouse wheel (both the big map and the mini-map). Plus you can scroll the list of characters on the side of the screen when in town using the mouse wheel if your list is large enough and goes beyond the screen.
Important note regarding screen zooming: There are set points when adjusting the screen zoom when the system has to redraw all of the characters in the world. This can cause a slight lag and an interruption in the character animations. This is done to optimize memory management as when you’re zoomed out farther you don’t need as high a resolution for individual graphics. So adjusting the zoom by large amounts too quickly and often may tax the system.
The combat screen now also has tooltips that display over most user interface elements, such as buttons. But the most useful one is hovering over ABILITY buttons as this will display detailed information on the ability without having to explicitly go into the ABILITIES screen.
Additionally, improvements have been made in appropriately scaling graphics for different screen sizes, especially higher-resolution screens. For new users, the game will sense the screen size and pick an appropriate scaling size. For existing users, you will likely have to tailor the scale to your screen size and preferences. There are now two sliders on the DISPLAY page of SETTINGS (prominently at the top) that allow you to adjust the scale for both in-town and in the world. Sliding these to the right will display text, UI elements, and pop-up windows larger, making them easier to see and read. Sliding them to the left will reduce their size. What level(s) you choose is a matter of personal preference.
Tips for adjusting your scaling level: Generally, if you have a screen resolution closer to 1920×1080, you will likely want to adjust both sliders to about 1/3 to 1/2 of the way from the left. If your screen resolution is closer to 2880×1800, slide it about 2/3 of the way from the left. You can fine-tune them left or right while on the various screens to see the resulting changes.
TO-HIT ROLLS: Rolling a 5 or less on a to-hit roll has always been a guaranteed hit (curse those lucky blind Goblins!). But now the same is true on the other end. Rolling a 96 or more is a guaranteed miss, no matter what your chance to hit was. This is only on the to-hit roll. It doesn’t not include the chance for a STATUS EFFECT (the 5 is not a guaranteed hit there either).
Another significant change … previously, if your chance to hit exceeded 100% the COMBAT LOG didn’t show the roll result because it was a guaranteed hit, even though it still was doing the roll behind the scenes to see if you scored a CRITICAL HIT. Now, the roll is displayed regardless. This just makes it easier to see the chance of a critical hit, it doesn’t change the outcome.
TRAPS: The system for traps has been completely overhauled. There are now two distinct phases to traps: DETECTION and DISARMING.
Everyone (but not monsters) has a 
DETECT TRAPS stat that is now displayed on the ATTRIBUTES screen. This is the chance that you will detect a trap before you activate it, giving you a chance to stop and decide whether to proceed. The percentage displayed is the chance to detect a simple trap. Moderate and sophisticated traps reduce the chance 15% and 30% respectively. Detect Traps is based on INTELLIGENCE and your level. But there are skills and gear to boost this, and Rangers and Rogues (Rogues more so) have natural abilities that boost this by their level.
Alongside this stat is 
DISARM TRAPS. Once a trap has been detected, a second attempt to interact with the trapped object (or to walk on the trapped square) will be an attempt to disarm it. The percentage displayed is the chance of success for a simple trap. Moderate and sophisticated traps reduce the chance 15% and 30% respectively. Disarm Traps is based on INTELLIGENCE, DEXTERITY, and your level. And similar to detecting, there are skills and gear you can acquire to boost it and Rangers and Rogues are naturally better at it (Rogues more so).
Once a trap has been detected, it is considered to have been found and any other action on that object (even by someone else in the party) or walking on the trapped grid square is considered to be an attempt to disarm it. If the disarm attempt fails, the trap will go off, either damaging the person in question, setting off a poison gas, or exploding (which usually destroys the object and its contents). Trapped containers that are detected will be indicated on the mini-map with the 
symbol and trapped ground squares with 
.
The number of traps and their complexities will increase depending on the level of the world. Generally, you won’t encounter traps prior to level 3. At level 10, there’s about a 6% chance that any given object that can be trapped is trapped. It is capped at about 15% near level 35. And you generally won’t see moderate traps appear until level 9 and sophisticated traps until level 15. Keep in mind that GAME DIFFICULTY can affect these stats.
As stated, monsters do not detect or disarm traps. If a player sets a ground trap, monsters cannot see these and automatically set them off when stepping on them. Players in the party, however, are aware of traps set by other players and can freely move past them without setting them off (this does not include summoned creatures). Monsters are, however, aware of traps set by members of their own group and can also move past them freely.
LOCKPICKING: Lockpicking has been changed significantly. As before, this is a skill that only Rogues have by default. Everyone else must acquire the base skill when leveling up in order to even attempt it (whether on a door or on a lockable container). Assuming you have obtained the requisite base skill (and you have a lockpick handy), the difficulty of the lock, your DEXTERITY, whether you are a Rogue, and possibly any skills or gear that boosts your ability will determine whether you can pick a lock. Each failed attempt has a fair chance of breaking the lockpick.
Your 
LOCKPICKING stat is displayed on the ATTRIBUTES screen. The percentage displayed is the chance of successfully picking a simple lock. You can click on the stat to see more details displayed in the tooltip. At the simplest level, a non-Rogue with no additional skills/gear and a DEXTERITY below 12 has a 20% chance to pick a simple lock. They have no chance of picking a moderate or complex lock. If you’re a Rogue or have a DEXTERITY of 12 or more, that expands your ability by one grade which means you have a 40% chance on a simple lock and 20% on a moderate lock. You still can’t pick complex locks. A DEXTERITY of 16 or higher boosts another grade. A Rogue with a DEXTERITY of 16 or higher gets 3 grades higher (1 for being a Rogue, 1 for DEX 12+, and 1 for DEX 16+). That equates to 80/60/40% for simple/moderate/complex locks. Throw in something like the SAFECRACKER skill or Safecracking Gloves and they’re guaranteed to always pick a simple lock, and have a 80/60% chance on moderate/complex locks.
Keep in mind that some objects may be both LOCKED and TRAPPED. You have to disarm a trap before you can attempt to pick the lock.
AREA-OF-EFFECT SIZING: Many abilities are AREA-OF-EFFECT or RANGED AREA-OF-EFFECT. These spread their effects over a circular-sized area, either surrounding the caster or surrounding a point within range that the caster chooses. However, as characters level up, slotting ATTRIBUTE POINTS to various attributes can increase the area-of-effect. Sometimes this can actually become cumbersome as the target circles get too large to manage and avoid collateral damage on allies. This is where AREA-OF-EFFECT SIZING comes into play.
First of all, to use this requires the character has invested in the 
AREA-OF-EFFECT CONTROL skill during upgrading. This is a SUPPORT skill available to all classes. If a character has this skill, when they go to target the ability and it is painted on the ground (either in yellow or red), using the mouse wheel will change the size of the target area, shrinking it or growing it. You are still limited by the maximum size specified in the ability’s specs, and the smallest is a 5-square “cross”. Once you have sized appropriately, merely click on one of the yellow/red squares to activate the ability.
RANDOM WORLDS: The Gate now has a checkbox at the bottom of the window that allows you to be randomly transported to any of the available worlds (provided you have the DLC). There is a 2% loot bonus per additional available world that is applied when the world is generated. So, if you’ve got the base game and all DLC unlocked, that’s an extra 10%.
NEW MONSTERS: The CAVE LURKER was added to The Caverns of Grimlock, the BROWN LURKER was added to The Hidden Realm, and the Swamp Lurker was added to The Swampy Isles. These are similar to other lurkers in other worlds, but lurkers are known to evolve and adapt to their environment, so don’t expect they will all be the same.
They’re not new, but (I believe) a bug had prevented the spawning of any ASWANG dens in any world. Aswangs came with The Swampy Isles DLC and can show up in other worlds. These vampiric undead blood-suckers fly on bat wings and are missing the entire lower half of their body. Their entrails dangle where their lower half used to be, and they slop blood and guts all over the place wherever they go. This mess is slippery and those that walk through it are likely to get knocked down. Aswangs are also HIGHLY sensitive to light and burn in direct light. As such, you’re likely only to encounter them at night or in dark dungeons or ruins.
NEW AND CHANGED ABILITIES: Several new abilities have been added to the base game, such as WATER SHOT and DETONATE (Alchemist), FLOOD (Druid), TELEPORT and DISARM TRAP (Mage), THROWN HAMMER and CIRCLE OF PROTECTION (Cleric), INDOMITABLE (Fighter), OPPORTUNITY ATTACK (Rogue), ABSORB ELEMENTS (Ranger), and SUMMON VALKYRIE (Paladin).
The former Mage spell OPEN HARD LOCK has been converted to OPEN MODERATE LOCK and is now the upgrade to OPEN SIMPLE LOCK. If you had OPEN HARD LOCK before, it is now OPEN MODERATE LOCK. Additionally, OPEN HARD LOCK has been added and that is the upgrade to OPEN MODERATE LOCK.
The range for the Mage spell PEER has been shortened, but it now detects traps.
Any type of active COUNTER ability will now automatically reduce your INITIATIVE so that you take your turn later in the round.
The Ranger/Rogue ability SNARE now automatically hits (but each effect applied still has its own roll)
The Swampy Isles adds the TIDAL WAVE (Druid) ability.
Special note: Many monsters with Rogue-type characteristics (e.g., KOBOLD, HOBGOBLIN GRUNT, WIGHT ROGUE) now have the OPPORTUNITY ATTACK ability. This ability allows them to take a free attack against anyone that passes through an adjacent square or were next to them and moves away. It does have a cooldown so is not always active, but can be potent.
CARRY WEIGHT: Carry weight is capped at 500 units regardless of your strength or skills.
CHARM AND DISEASE RESISTANCE: 
CHARM RESISTANCE used to be based entirely on CHARISMA. It is now a combination of both CHARISMA and INTELLIGENCE (but skews slightly more favorably to INTELLIGENCE). Plus MORALE significantly affects it. And it can be affected by both skills and abilities. It isn’t explicitly displayed on the ATTRIBUTES screen, but know that these are the factors that contribute toward it.
ANGELIC creatures can’t be charmed (there’s currently only one of these — the Valkyrie from the Paladin’s SUMMON VALKYRIE ability).
DISEASE RESISTANCE is still based on FORTITUDE, and Rangers and Druids get 50% more than others per FORTITUDE point. But there are abilities and skills and gear that can boost this.
It is also noteworthy to point out that the Cleric ability ANAHATA (The Frozen Expanse DLC) now includes some DISEASE RESISTANCE.
FIRE AND WATER: Some effects from abilities are now 
FLAMMABLE. If they come in contact with an open flame, or are in a square adjacent to an open flame (like a campfire, ground torch, MOLOTOV COCKTAIL, etc.). During combat, these effects will ignite and spread. They will spread one adjacent square in all directions (that has a flammable object) BETWEEN EACH CHARACTER’S TURN (fire spreads quickly). Anyone standing in the affected square will immediately take fire damage. Fire, of course, will not spread on water or a wet square.
Some abilities are 
WATER-based and can do damage to susceptible creatures (typically fire-based creatures like FIRE BEETLES, FIRE GIANTS, MAGMA MEPHITS, etc.). But to others being wet is just being wet and does no real harm. This list of water-based abilities includes new ones such as WATER SHOT (Alchemist), FLOOD (Druid), and TIDAL WAVE (Druid/The Swampy Isles DLC). But this has also been extended to existing abilities such as THUNDERSTORM (Cleric) and WET IN A BOTTLE (Alchemist).
Many of these water-based abilities can also extinguish ground fires (think campfires, ground torches, or MOLOTOV COCKTAIL).
CHANGES AT THE MERCHANT: The Merchant receives new inventory every month. However, these will now be highlighted in the list with a NEW symbol in the corner of the icon for the first month.
The Merchant also now offers a LAYAWAY plan for expensive items. For 10% down, he will hold the item for 12 months until you purchase it. As long as you pay the remaining 90% within that time, the item is yours. If you don’t pay the remainder, you forfeit the deposit and the item goes back into the regular stock and is subject to normal rotation. To put an item on layaway, just select it and press the 
button.
Also, the prices of 
SPIRIT weapons were prohibitively expensive. These have been reduced (a lot).
BETTER LOOT: The frequency and quality of weapons and armor found in the field has been increased.
There were also a ton of small bug fixes and patches with version 1.1 (build 75). You can see the full list here: https://www.infinitedungeoncrawler.com/release-notes/.