I've got two games I've been thinking about for years but haven't tried to figure out what they are.
(Both were when I was a kid so it would be around the PS1 era. Not necessarily on the PS1 though)
Game 1: top down camera. 2d game, or at least 2d characters. Very colorful but I remember very specifically an auto scrolling lava type level with a narrow path going up and lava bouncing around as well as enemies spawning. Here's a unique thing about the game: whenever a person died, an icon pops up where they died that shows your characters icon. You can press left and right so switch the character you are. These icons are pixel art. That's all I got.
Game 2: Think contra hard corps as a base. You're a regular looking dude, possibly with melee weapon but likely just shooting stuff. I remember the background looking like a field of trees / mountains in the distance and it scrolled for this boss. The boss is a giant metal robot looking thing you see off in the distance, then it jumps into the area under you. There are walls on the left and right side of you and platforms connecting the walls. You need to jump up the platforms while fighting the boss and there's a lot of scrolling / action.