Raiders- Capture the Jewel (green arrow) and bring it to the ufo (another green arrow) through any means!
Guards- Protect the Jewel (blue light in the sky) without getting too close, and don't go past barricades (they hurt)!
Most things will be explained in game, but there is still more for you to find out!
Raiders - Get the Jewel in the base and bring it to the friendly aliens (follow green arrows)
Guards - Protect the Jewel without going too close or being too far away
Have fun and be friendly with each other, you can do more than just attacking/defending