Version 4 improves realtime lighting performance in most levels, though levels like Level 07: Catwalks may still be slow. Some levels got extended areas, Level 08: Blood Processing got more blood and there's more toxic slime in Level 04. Player's weapons got adjustments.
There's also new sounds for Fiends, Demon Spawn and Flying Maggots. The ingame messages can be translated, currently there's: English, Finnish and R'lyehian translations.
Here's more detailed changes:
Levels:
- Total 3000 monsters on Hard and 50 secrets
- Level structures block rendering visibility more
- Nearly all see through grates are now also shoot through in all levels
- Level 01 has the secret yard teleporter two way
- Level 02 has more moving platforms at the end
- Level 03 has the starting area extended and wider sewer corridors
- Level 04 has the ending area extended
- Level 05 got some cover blocks to the water area
- Level 06 has the red key teleporter two way
- Level 08 has the two areas extended
- Level 09 has some cover blocks in the area after the blue key
- Secret 99 has the spikeroom exterior extended and the quicksand changed to water
Player:
- Simplified armor to just 3 types: 33% Light, 50% Combat and 66% Mega
- Player can no longer jump over enemies to safety
- Player can jump/climb up walls a little higher than before (need to look at the wall to get up)
- Player's ammo capacity has been increased, no longer need backpacks to increase ammo capacity
Weapons:
- Ripper now has a limited supply of Chain Lightning attacks up to 9, recharges slowly up to 3 and can be used underwater
- You get Double Magnums from finding another pistol instead of the powerup
- Railgun now shoots multiple pellets that can pierce enemies and blast them into walls and uses Shells for ammo
- Machinegun only has one fire mode: full automatic at 1200rpm
- Grenade Launcher shoots incendiary grenades
- Rocket Launcher primary mode is dumb rockets and alternate fire is guided if you have some guided missiles
- Flamethrower is more devastating and has less ammo
- Plasmagun alternate fire no longer automatically homes into targets, you need to guide it yourself
- The Sword that appeared as reward in Secret 99 got removed and replaced with 3x Soul Crystals
Powerups:
- Power Ammo now gives 30s of Double Damage
- Magnum Power turbo shots, Lightning Shield strikes and Protective Suit degrade over time even when not actively used
- Lightning Shield can be used underwater
- Invisibility works underwater, the circuits have been waterproofed
- Catnomicons now give Combat, Armor, Treatment and Sporty powerups for the duration of the level
- New powerup: Soul Crystal, permanently increases max health by 1, total 17 in episode 1
- Backpacks are left into the level for later, if player can't pick up all the ammo from them
New sounds:
- Flying Maggots
- Fiends
- Demon Spawn
Other Changes:
- Possible to disable monsters from casting shadows, can speed up realtime lighting
- Crosshair can display target health status, default on
- Particle shape can be changed between: Textured, Circle and Sharp Square (textured is still just the rounded square)
- The ingame messages can be translated, currently there's: English, Finnish and R'lyehian translations
- The 256 color palette got greener greens and more saturated purples
- Fixed inaccuracy issues with hitscan enemies, they were shooting completely off target, now they have other kind of inaccuracy
- Ambush monsters notice player better