In need of a bit mindless shooting fix I got in a few rounds of the Team Fortress 2 custom map "Balloon Race" last night. Its a very fun map with a little bit of strategy to it. The aim of the game is to capture a set of control points which you can only get to by flying there in an airship. In order to make the airship fly one or more players must stand at the wheel in front of the ship. If you die you instantly re-spawn back at base but you can jump down a hole and immediately get tele-ported to the ship. Its alot of fun combining the race betwen points with all out firefights at the control points.
I think it is a lot of fun but I have seen the map criticised as imbalanced because if one ship gets a bit of a lead it can be very hard to catch up. This mainly happens becuase a lot of players have no clue how to play and dont bother standing at the wheel to get their boat moving. THere are actually pplenty of starategies you can try. You can try to snipe the helmsman (which is harder than it should be from behind admittedly) or if you know you are going to lose a point you can make sure your ship has a bit of momentum so you get a head start to the next one.
The map does favour some classes more than others. Engineers and Spies have limited use although there are a few places on the map where a well placed sentry gun could wreak havoc. Heavies and soldiers are probably the best classes for manning the wheel. Scouts should be useful for quick captures but are not very popular on the server I play. Pyros and demo-men come into their own in the frantic fights at control points while snipers are invaluable for taking out the oppositions helmsman. My favourite character is a soldier because they are tough enough to man the wheel or capture a control point while their rocket launcher has the range and power to successfully kill the enemy helmsman. The game doesn't implement relative velocity properly though so you need to forget the laws of physics in order to hit your target from a moving boat.
The high score table is pretty pointless though rewarding kills and captures only. Just killing enemies cnan do more harm than good because they respawn instantly with full health and ammo and can zap straight back to the boat. A smart player will focus on keeping the boat moving and only worry about killing the enemy helmsman or an enemy trying to capture a point.