Late '90s/Early 2000s Cartoony Isometric Sci-Fi Action Game

I remember playing this game daily at my friend's house as a kid, and have been trying to find it again for the better part of 2 decades.

The graphics are very cartoony, with an isometric camera projection. The main character was a white male that kind of looks like an embellished version of Superman, except he has no superpowers. Instead he has a gun, which to some people is a superpower I guess.

Gameplay-wise you basically just shoot up hordes of enemies and their basecamp. You can shoot crates which gives you ammo and grenades. There are different types of grenades, one of which is like a miniature nuke.

The game has a co-op mode where the 2nd player is a black male with the exact same physical features, except his clothes are a different colour.

When you finish the first stage you get to a cutscene where the MC flies away in his space van. Think Lonestar's van in Spaceballs.

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That's basically all I remember.

Edit: Forgot to mention, I played it on PC, but don't know if it was a PC-exclusive game.