Install SDL2 development core and image libraries. For instance, on debian or ubuntu you use: sudo apt-get install libsdl2-dev libsdl2-image-dev
make
./knikkers
The undo button in the bottomleft takes you back a step, while the mark in the top right of the board indicates whether calculation is busy (you can still make moves while calculating), or whether the game is still winnable (green checkmark) or not (red cross).