The Random Red Guy is a piece of unused NPC from Metal Slug X. he would be used as a background NPC, and his sprites suggest that he would be in a window. He has different animations; in one he is yelling, and in the other he is startled and taking cover - suggesting he would react to either the player or the enemy's actions. It is unknown why he was scrapped, although the most logical reason would be avoiding the implication that civilians were harmed by the fight.