5 , 6 , 7 and 8 : By default, you must use these four keys to make your currently-selected Thunderbird fly to the left, to the right, up and down; you may also press A to switch from Thunderbird 1 to Thunderbird 2 (and back again), R on the title screen to redefine the keys, M to turn the music (which is a General Instrument AY-3-8910 or a Commodore SID rendition of the show's theme song by Barry Gray, 1908-1984), P to pause, S to save your current position to the cassette, and L to load a previously saved position from the cassette (a very early example of savestates).
The protagonists of the game; due to technical limitations, they're coloured blue (or gray in the C64 version) and green respectively. Before taking off, you must decide what equipment you need - however, Thunderbird 2 (piloted by Virgil Tracy) only has a maximum payload of 40 tons. Blue (gray in the C64 version) blocks may only get moved by Thunderbird 1 (piloted by Scott Tracy), while green ones may only be moved by Thunderbird 2; however, red ones may be moved by both of them. Both Thunderbirds can not occupy the same space simultaneously - but each load of treasure they collect is worth 100 points, and fuel pickups will give them two additional minutes' flying time each.
