I feel totally stupid: impossible to find the key corresponding to the jump. Two possibilities :
1) it exists, it's quite stupid, but I can't find it despite my many tests (and it is then urgent to specify it in the game page so that the other players/testers are not blocked like me).
2) there isn't, and it's of the same ilk as the "Nothing" project with situational humor (but oddly, since the game is classic in its form, the humor is less perceptible)
I therefore have all the trouble in the world to know what to write and how to vote for this project. Is this an error on my part, bugs, or a humorous will of the developer? Never hesitate to clarify things somewhere anyway, whether in the game page, or in devlog articles.