Some of the characters in the game, like Adam, are just typical character designs of the era (late 80s/early 90s) Same somewhat with Axel. Also the same with several enemies. Skate seems to be a reference to DJ Boy, but also, as Brawl said, a representation of the inline skating fad. Max is obviously Mike Haggar in moveset. As for Zan, I cannot confirm this, but something gives me a Dragonball Z feel with his design and possibly moveset. In terms of appearance, I am not sure if this was intended or not, but Barbon looks pretty similar to Haggar in the face.
If we were to turn things around, Gren from Dungeon magic looks exactly like Max. To the point I think he may have been inspired by him.