I think Amos Pro (BASIC) is the most popular game programming language on the Amiga but it isn't as powerful as Blitz Basic 2, which seems to be able to create more professional looking, faster games. Some commercial games even used it.
And if you don't want to code, you could try Backbone from the Aminet, it's a game maker program with lots of features.
And if you are really interested in making Amiga games, maybe you could join our team, Underground Arcade!