SuperTux is a classic 2D jump'n run sidescroller game in a style similar to the original SuperMario games.
The jumping is not ok. Began thinking of this during the first 10s of the 1st level and it got worse. Also the running is hard to fix on a keyboard. I understand its a free game, so I'm sorry for the down-vote, but have received my share of the same with no explanation. At least I gave an explanation.