Sharing this more as an idea than anything else - I am clearly NOT going to release a level THAT stolen.
https://www.youtube.com/watch?v=MKYz26R9xpE
Explanation how it works (also in video description):
The trick to keep Tux's y coordinate moving at constant speed was a second solid tilemap that is moving on a path. The small spike was done by having a third tilemap that moves half a tile down (one-shot) at level start. The trick to reset music every death was a sector init script that does
play_music("");
play_music("/the/background.music");
to "reset" the music. Game physics have been modified by doing
set_game_speed(0.6);
in the same trigger and by setting gravity to 16.
Note that triple spike jumps are IMPOSSIBLE in this, as SuperTux's spike hitboxes are criminal.