I'm using Backbone to make my Halloween Nightmare platform game. Although it is buggy, once you know where the bugs are you can avoid most of them. It's really worth giving it a go, because it has SO many options for customising your games. Sure it lacks a few features (like ammo, currency/shops, switchable/selectable weapons, high score table) it still has enough to make your own fun platform games.
Backbone was originally programmed in Amos Pro, but parts of it were re-coded in C or ASM or something. Unfortunately the games still run as slow as an Amos game. You can see an example of what Backbone can do if you want to try my game demo, I'm sorry I haven't made an updated demo yet. The old one is here though -
http://aminet.net/package/game/demo/HalloweenNightmareDemoI think it's a good way of making prototypes for games that you could maybe later on code from scratch. I'm hoping I can find someone who can code this Halloween game, because it's going to be quite large with lots of levels and characters.
I have always wanted to try out GRAC2 or GRAAL, as well as Reality, but I just haven't had a chance. GRAC2 looks easy enough to use, and can make some very decent adventure games (if they're playtested well enough). Reality looks quite complicated. My boyfriend bought a copy of it as well, but the documentation was just a photocopied piece of paper. I'll have to dig up the CU Amiga magazine that came out later on, I have the CD for it here (the one being sold on eBay, shame on that pirate!).
I really hope you find something that will help you make the game you want! :kitty:
