A team-based, light RPG skirmish game. Think of a game that's part Counterstrike, part Battlefield: Etc, part Nox, part JKO, part Mordheim, and part D&D. Each team would have a number of adventurers in adventure-based levels. One could be in a dungeon, another in a medieval town, and another in some ruins in the forest, whatever.
The object would be gaining treasure. Perhaps you need to steal treasure from the other party (warband, etc) (kind of like CTF), perhaps you need to protect treasure from the opposing party (like in the Battlefield series). Perhaps the treasure you obtain can be used, like a magic sword or wand (or maybe this kind of stuff is around the battlefield like in Nox). Maybe one of the modes could be "Artifact", where you need to obtain all the artifacts around the field, and each artifact is really powerful, where another mode could be infiltration style where you need to go into the opposition's base and steal their gold and jewels.
There would be a number of classes to choose from, similar to Nox and D&D. There would be a warrior class, obviously, who is the best at straightforward fighting. There would be a wizard class (possibly more than one kind, like in Nox... wizard/conjurer). There would also be a thief class... more versatile than the others (for instance, could use weapons better than the wizard, and some magic items warriors can't use), with the ability to hide in shadows and do massive damage when attacking from behind. Maybe even the ability to scale walls with a grappling hook or something. Perhaps a cleric class who would be second only to the warrior with fighting. Or maybe the cleric could be more powerful than the warrior but the warrior is more dexterous or something.
Combat would be deep as in JKO, and strategic as in Nox. Instead of just a single swing with the sword, there could be different moves just as in JKO. Wizards could have all sorts of cool spells, such as damage spells, utility spells (such as a kind of Force push or pull), buff spells and more, with a spellbook that allows key bindings, as in Nox. Perhaps we could even have conjuring.
There may even be leveling up in the game. In many team-based games there’s little reason to kill unless you are defending or attacking a base. In this game we might make it so you gain experience after every kill, with a quick level-up option. Perhaps you can configure your character before the game so that leveling is instant and you gain whatever you chose beforehand so you don’t need to stop playing to level.
I think the Half Life 2 engine would be perfect for a game like this. We could make a mod. What do you guys think? We’d obviously have to recruit some people but I think it could be great.