I Agree, its a New level of RTS Gameplay, I propose the Building to be Captured, (Think in a Fortress) have a low HP or Healt about 40%, and units to take it maybe like RTW have to Garrision to Star a bar of Capturing 0% to 100% .Now we had a Problem what happens with Ally(ally to Fortress in this case) Garrisoned unit, may be can be Expulsed if the are a 1/3 of Attakers numbers. For example 3 Defenders against 9 attakers.