For one player mode and player 1 for two players mode, operate the red ribosome by arrow keys.
For player 2 for two players mode, operate the blue ribosome
by wsad keys (up, down, left, and right, respectively).
Move the ribosome to get the amino acid directed in the bottom left of the window (see below figure) in the order.
The stage completes when all the amino acids are collected.
In the hard mode, the game finished when the ribosome hits to the wall, the opponent player, or the own tail of protein chain.