Hey, I'm the creator of Infernity - a mod for vanilla diablo that could be considered the expansion that hellfire was supposed to be.
I'm avoiding any drastic changes, keeping the core gameplay intact while improving the game.
Let me describe some of the features.
A new difficulty called Inferno.
Special items with an additional affix can drop there.
The additional affix will only appear if the item has a suffix and a prefix or is a unique item. Additional affix doesn't follow the regular prefix/suffix rules, which mean that combinations that weren't possible before can occur. This is the most important change. A persistent mage might find himself using a thinking cap with additional affix giving +2 spell levels, which would mean that the TC gives +4 to spells total However finding perfect items will take you years, so it's something to strive for!
Also revived old difficulties - items dropped there will have increased levels. It was just pointless that while you've fought harder/more difficult monsters on nightmare/hell, the items they'd drop would be exactly the same as their puny versions on normal difficulty. This is a natural change.
Compatibility with vanilla, but sadly in one direction = you can move your vanilla character to infernity, but if you move character from infernity to vanilla, items will morph like crazy (This is because inferno items have increased level to enable them to get the "dead" affixes (the ones you could only get from Wirt) - if you had a nice character in vanilla diablo, it's not lost! You can keep playing on it in Infernity.
Running in town/dungeon - reducing a trip to Adria from 5 minutes to 2.5 ...
Highlighting enemies in combat
A config to enable or disable stuff
Fully shared xp - you don't need to poke or even be close! Seems in vanilla diablo the xp would be divided between the killers. In Infernity everyone gets 100% xp, so splitting to clear faster might be a good idea - when I play with friends, I don't want to get punished with reduced xp. This change seems small but adds a lot of depth to the game - for fastest lvling you should split and clean different parts of the level!
Black death doesn't permanently decrease health anymore! - same as mana reducing shrines, just no.
Added xp bar - yet another small but amazing feature that is a must have for games like diablo.
Minimap is shared between players - a cool feature, when you play with your friends, not only you can see their position on the minimap, but the map they explore appears for you in a different color! So you won't be running around without reason because you don't know which parts of the dungeon have been cleaned already.
Gold pile max size increased to 60k (Can't be more because of variable type - at least for now) - I'm planning to remove gold completely and keep it on the player as it's just cluttering the inventory, but for now increasing gold pile size to 60k does the trick. There isn't anything to spend the gold on anyway, the game needs something to give gold a meaning
Shop selection stays after buying item (it used to reset to first top item before) - I think it was just an oversight on blizzard's part that they didn't add this. It was so annoying that you could only buy small mana/health potions by holding enter because they were first on the list. Now you can do that with any item.
Shift clicking potions in inventory adds them to belt - yet another small feature that makes playing more convenient and what we got used to from modern games.
Remove/change permanent negative shrines (In general, things permanently damaging your character) - I'm totally ok with temporary debuffs, but clicking one shrine and ruining your character forever is just a big no.
Show shrine effect in the description - saves alt+tab and googling the shrine name
Expand inventory (4tabs, switch by clicking on the icon or shift+1/2/3/4) - 4x10 space simply wasn't enough for a game where you could find so many nice items. This is very helpful as it reduces trips to town (you can carry 4x more potions as before after all).
Make the map revealed by the shrine have a different color - Shrine revealing the whole map was useless before, because you couldn't know what part you've explored already and what you have not. This change deals with the problem.
Add monster resistances/immunities on the health bar - no point in having a nice health bar if it doesn't contain as much useful info as possible.
Show other players on minimap - a nice addition to multiplayer, now you will know where your team is.
Items won't drop on death - While this added an element of risk and uncertainty to the game, I disliked it because you could find yourself losing all your items because of a crash or desync in multiplayer. When I die, I'm ok with some temporary penalty or xp loss, but not losing all items that I've farmed hard for who knows how many days/months.
Fix friendly fire - the player friendly/hostile buttons in multiplayer weren't serving any purpose. I fixed that. It was close to impossible to play with a mage that was quick to cast his spells. Now they will hit what they were intended to.
Diablo is a unique monster and drops items - more on higher difficulties - I've always been a little disappointed that Diablo, the ultimate challenge and final boss, hell, even the game is named after him, didn't drop any items! He wasn't even considered a unique monster! This mod fixes this shameless oversight The game doesn't end anymore after killing diablo, you can take his loot and keep playing.
Showing current/max on health/mana orbs - optional. You can enable/disable it in config. Some players (including myself) love numbers and it's really handy to see the exact amount of health/mana you got.
Alternate weapon slot + switching between weapons - It might seem a ripoff from d2, but I think it belongs more to d1 than d2. Switching weapons is a must have for a warrior (remember that blunt weapons deal 150% damage to undead, 50% to beasts, while sharp weapons deal 150% damage to beasts and 50% damage to undead). Switching weapons from your inventory was clunky and unnatural, now having 2 sets of weapons is just like it should be.
Fixed duping - I always disliked this as it removed a lot of depth from the game, making gold/elixirs/amazing rings meaningless.
HD - right now it supports resolution up to 2560x1440, I've even managed to run it in 4k but it seems diablo/directdraw isn't just supposed to handle that much - while I've been able to see the map, the cursor wasn't there Everything was so tiny! To achieve different resolutions than diablo was supposed to work in, I had to modify both diablo's code and ddraw.dll, so for playing Infernity you need my own custom ddraw.dll. The original one won't work.
Stash (You can only use it in town, you can quickswitch to it using Shift+5) - when you are in town, a new button appears in inventory which can be used to open/close the stash. It's basically an addition of 100 inventory tabs accessible only in town. How to put items there? With further development I might consider adding an intermediary inventyory area for putting items from/to stash comfortably, but at this moment you could drop items from inventory to the ground, switch to stash and pick them up. Or you could pick the item, switch from inv to stash using Shift+5 combination or Shift+1/2/3/4 to switch from stash to respective inventory tab. You don't have to worry about space for magnificent finds anymore You can even name your stash tabs!
TrueColor support - What does it mean? It means that I can display 16 million of colors. At the time when I'm writing this, there aren't any elements in the mod that are using new colors, but the possibiliy is there and I'm in the process of creating a loot filter which will let users define custom colors for their loot
Sprite limit raised to 10k - in original diablo this was 125. That's the thing that caused chain lightning pieces to disappear, when you spammed firewall, you'd find yourself unable to cast more spells till the firewalls expired - enemies couldn't cast/fire projectiles as well. With increasing the limit to 10k you shouldn't be worried about hitting it anymore All spells are really nice and smooth!
Spell hotkeys - the vanilla game had only 4 hotkeys - F5-F8 keys. I've made all F keys hotkeys, which mean you can have up to 12! F1-F12. Another thing that was very bad was that the hotkeys wouldn't save. So you had to reassign them every game. Imagine doing that for 12 instead of 4? No more. They save both in single and multiplayer.
PVPGN SUPPORT! That's right! For those that don't know what it means, it means you can play on battle.net emulation servers, which (what a surprise) are supposed to work just like battle.net for diablo 1. I've included a reg file in the mod pack on Moddb which adds new gateways. Now multiplayer is just a few clicks away like it was in the original diablo. No need to download third-party programs like Tunngle(RIP)/Evolve/Gameranger/whatever
Hope I haven't bored you to death!
This is just the beginning.
The goal is for Infernity to become the ultimate mod
A lot of new features/improvements are going to come.