SpaceChem has several hotkeys to make it quicker to build reactors and Waldo cycles.


The arrows and the other common instructions are created by holding the relevant key down and clicking on the grid.


Arrows W-blue
Arrows WASD-blue

Other instructionsEdit


  • Tab: Switch between red and blue

Mouse commandsEdit

Left mouse click to select an instruction or to drag it to another place.

Right mouse click an instruction on the grid to select variations or to change its color.

Select multiple instructions by dragging a box around them, starting from a place where there's no symbol under the cursor. Shift + left click adds/removes symbol to selection.

Copy: Mark instructions, then use CTRL + mouse to duplicate all marked symbols. Hold CTRL and drag selection to a free area on the grid.

Other commandsEdit

Ctrl H F1234 B-C-activated

Highlighted Controls "B" and "C" are activated (switched on).

  • Undo: Ctrl-Z , Redo: Ctrl-Y
  • Delete: removes selected symbol(s) from the grid
  • 1, 2, 3, 4 number keys to select speed
  • Play/pause: space bar
  • Stop cycle/turns: tilde key (~ , press key under Esc)
  • F1, F2, F3, F4: Controls can only be used in defence assignments

See alsoEdit