This would be pretty cool, but maybe only include a few (not all destructable by weapons) brick types, and give each player a brick limit of 100 or so per type. Custom weapons and classes for this would be cool, like Sourceforts. I'm thinking maybe a fast running class with weak weapons, a slow running class with powerful weapons, and normal running class with decent weapons and one that can also destroy enemy bricks with some kind of weapon (takes a few seconds per brick, though). This makes it so you won't build with only big bricks because when they're destroyed they'll leave huge gaps, and that you won't only build with small bricks because they can be destroyed with weapons.
Example classes:
Scout:
-Pistol and Sword
-offensive
-runs 2x faster and jumps 1.33x higher (8 bricks high)
Engineer:
-Shotgun (weaker than ephi's 1-shot one) and Screwdriver (to dismantle/destroy the enemy base)
-strategic
-run and jump is default
Soldier:
-Rocket Launcher (but fires slower than the default one) and some kind of fairly weak machine gun, maybe Uzi
-defensive
-runs 1/2 as fast and jumps 2/3 as high (4 bricks high)
Sniper:
-Sniper Rifle (takes only 70 health to prevent 1 shot kills and sniper rape) and some kind of custom melee weapon that kills in 2 or so hits (a dagger or something)
-support
-runs 3/4 as fast and jumps the same height
TF2 rip-off names but whatever I couldn't think of anything else. Maybe Runner for Scout and Dismantler for Engineer. idk.
Well those are my ideas. I'm not sure if you can edit player health, but if you can the Scout would have 70, Engineer 100, Soldier 130, Sniper 85 or something. As far as rounds go, maybe a 15-20 minute build phase, 10 minute attack, 5 minute repair and then 10 minute attack again. Whoever has the most captures at the end wins.