In addition, the minimal AI is necessary because of the 8 directions and the terrain. Commando is good but scrolls in one direction. Enemies do not follow you or watch collision of each other. The 8 direction of control over 3 enemies results a visible slowdown on a stock machine (as we have tried to prepare the engine for many things). Enemie features:
-follow (up to shooting distance or punch distance)
-saves his position (if I go back you will be there)
-watches the terrain, trying to avoid objects/walls
-surround you instead of settling in one place / line up in row
-looks for a new position if he missing the shoot
-walk away or escapes if hit by bullet.
-have the ability to hit, shoot, throw grenades, some can even summon help ;)
-terrain can also be destroyed by the enemy
-the two camps can shoot each other.
-NPC follows you/ helps as above
...and all that is just for the emenies, but there are other items, sound/music, bullets, anims, HUD, Camera, player, npc, weapons, MAP and and try to handle 255 MAPevent in every single frame for the player and for the enemies and still remain at playabe speed.
A stock amiga is not a power plant and all that we program in BASIC... what we learn almost as we write.