MISP allows for the new- and old-school FPS mechanic-fusing Project MSX to be played in Hacx 2.0, Heretic, Hexen and Strife, as well as custom levels for these games, provided they're just maps and don't modify weapons, items, the player, etc.
As MSX had custom enemies, so too does MISP for each of the games it supports. While the methods to defeat them are rarely different from their vanilla equivalents (hint: shoot them), here is some information on some of the foes you can expect to find.
Previous players of MSX will notice some new powerups and new icons in the HUD, depending on which IWAD they're playing. These are explained below:
MISP Version 12.28.13
-Make sure you have the new version of Project MSX! MISP consists only of patches for MSX and does not contain the actual mod.
-Load the compat.pk3 for the IWAD you're playing AFTER projectmsx_v0.2.pk3.
-Strife & Hexen: You may survive some falls that would've killed you. I've set the player's falling damage multiplier to 3.0 for these games and done some testing, and it seems to work well, resulting in death when dealing with exremely long falls (i.e. the Guardian of Fire crumbling hallway that leads to the Flame Mask), but still giving you some leeway with shorter falls (i.e. the narrow walkway in the Ordeal map in Deathkings of the Dark Citadel, and the pit room in the alternate path to the Oracle's altar in Strife.). It may need to be tweaked, however.
-Strife: When your shield is at full, it repeats a neverending sound that goes away when you take damage, and comes back when it recharges to full again.
It's Not a Bug, It's a Feature(TM):
-You can sprint while flying in Heretic & Hexen. I may or may not take this out.
MagSigmaX for Project MSX.
Large Raptor, Taurus and Hydra ammo pickup sprites based on, with edits, Real_Trisk's large Chimera ammo pickup sprite in Project MSX.
Jet Booster pickup sprite based on Russian Overkill shield pickup sprite by PillowBlaster.
Bormoreth based on DBThanatos' & Tormentor667's Bormoreth at Realm667.
Alchemist throwing animation from MagicWizard's Melee Disciple monster at Realm667.
Lava Demon from Realm667 by Virtue & CodenniumRed. Alternate 'cooling' death sprites are edits of mine based on Lava Demon sprites.
Magma Serpent from Realm667 by Fury3 & Ichor.