ctf_invade is a small-ish invasion ctf map. The goal of each team is to bring a neutral bomb to a death located at the other team's base. the catch? If the bomb is dropped and isn't picked up within 10 seconds, the bomb will become neutral and will stay at it's spot for 10 more seconds before resetting.
The map has 3 main paths:
Mid: Probably where most of the action will take place, this is also where the bomb spawns.
Trench: North of mid. There is a large ammo box located in the trench itself, but dropping down into the trench from mid will probably hurt.
Courtyard: A large, open area south of mid. on both sides of the courtyard, there is a small building that is ideal for snipers to shoot at each other form both sides of the courtyard, just be careful of other classes sneaking up on you from the courtyard itself. There is also a small deathpit further south of the courtyard that is home to a large health kit, just be careful of pyros who do things other than w+m1, though, as they could easily push you off.