+1 for the epic old school style ^__^ You know I do believe it would be quite simple to use the alien swarm version of the source engine to make something like this ... Got a gut on ModDB making a half life source top down version on that engine too.
omg Abuse was awesome. But my opinion is that Abuse was cool mainly because of the WSAD + mouse control scheme, for a sidescroller nontheless! If crusader had that, to give far greater control and twitch gameplay that would be sweet.
XCOM anyone? Namely XCOM Apoc's realtime mode with Jim Hatama art <: o
The controls were truly brilliant for its time. Now games like Trine make the genre look far more vivid, but Abuse really started that entire scheme. If I recall, the game's level editor was fairly sophisticated, including a whole array of Boolean logic functions for linking its interactive objects.
Crusader...wow, I gotta find my CD. Time to fire up DOSBox!