Tumba is simple enough: stack the blocks, and if they fall, you lose. What throws the game into a deep realm of creativity and planning is that each block has five sections of differing colors: red, green, yellow, orange, and blue. When placing a block, the color must rest on top of the color below it. Blocks can be on their ends (a structurally risky maneuver, but perhaps clever in that the other players in the round must work with a potentially weak piece), on their sides (the most reasonable way to place: find the middle color and match it for balance), or even as bridges (which give support from weight pressing on less stable pieces, like an arch).
No two Tumba games go exactly the same. The game begins with a player placing the first block on the wooden plinth, either in the single parallel groove or one of a pair of parallel grooves, which will make for more stability if players are feeling conservative. Thus, even at the beginning the game has room for choice and possibility.
Blocks are drawn out of a handy bag, giving randomness to what piece will come up when. With fifty pieces and five colors in varying combinations, the odds of prediction are astronomical, making for a game where players have to be very quick on their feet. House rules may decide whether two hands are allowed, but everyone knows that as soon as a player lets go of a block, it has to stay there.
With so much randomness, there is the possibility that a block cannot be feasibly played. In this case, there is the option of calling a “no play,” upon which the calling player may put the block back and draw another. Other players may “challenge” the call of a “no play,” and if they are able to determine that the piece is in fact playable, the “no call” player is eliminated. The rules call for a tournament style of game with more than two players, eliminating at-fault players when the tower collapses (with the obligatory shout of “Tumba!”) until a winner is proven. There are also rules for single-play seeing how well one can stack.