The Tribe is an expansion pack for Gratuitous Space Battles. It's for people who have played the original game enough that they crave new ship designs and scenarios, and want more variety in the game. It includes:
11 New ships. 4 Cruisers 3 Frigates and 4 fighters, all in a new graphical style by the same artist who did the original GSB artwork.
1 New weapon type: The kinetic weapon. Basically autocannons, howitzers etc. These fire rapid-fire bursts which are good at short range, not so good at long range
Enhanced repair modules. The tribe are great at repair, and their repair modules are race-specific and out-perform everyone else's.
New ship bonuses. The tribe ships have only half the shield and armor strength of everyone else, but they have twice as strong hulls as their opponents. This means Tribe ships seem to be on-fire and falling apart for half the battle. It also means you need to re-think your tactics.
2 New Scenarios. Two maps for you to fight against the tribe, or for you to use in uploaded challenges with whichever fleet you like.