Years ago, when Half-Life 2 came out, I thought an Apocalypse War scenario would make for a good game. Not a novel idea, as I'm sure anyone who's played HL2 or Medal of Honor type games has thought much the same. Anyway...
You'd be a Rookie heading in to the Halls of Justice one morning, and after wandering around, drinking in the atmos, you'd take a combat exam, which'd be a weapons training level, then a nice Lawmaster training bit.
Suddenly disaster strikes, East Meg missiles hit MC1. You find your way out of the ruins and set about progressing through the city, encountering Blockmaniacs, Sentenoids, Rad-Sweepers, Sov troops etc, and hooking up at times with Citi-Def units and other Judges. Partly mission based, and partly just making your way through the ruins, you'd take part in events such as getting the CJ out of the city, regaining Weather Control, and accompaning Dredd on the Strato-V to EM-1.
Tooling around on a Lawmaster (in some levels), and scavenging ammo against the backdrop of a city in chaos, with intermitent orders from Comm, and grim news broadcasts, is my idea of a fun MC-1 game.
I just remembered that I thought a cute idea would be that you'd come across a Tek lab with early Mechanismo prototypes, and you'd spend a level with your brain plugged into a Mechanismo (remote controlling it) in order to destroy heavy opposition so you could progess. Hell, now that I think about it, you could stumble across a Land Raider, and a Manta Tank too! Why not? :-p