Heya!
I'm Semphris, quite new to the forums! Those that aren't on the Discord server might not know me, but I'm the newest developer in the team! I'm the guy who spawned features obsessively for the past year and a half, including the WASM/browser port, the Ubuntu Touch builds, the particle editor, bezier curves, easing, and plenty of other features and bugfixes which you can find a list here: https://github.com/SuperTux/supertux/releases/tag/v0.6.3
Well, my latest job was to release SuperTux on Steam and Newgrounds. You can find the links to both here:
Steam: https://store.steampowered.com/app/1572920/SuperTux
Newgrounds: https://www.newgrounds.com/portal/view/827528
Note that Steam asked that the store page should remain as "Coming Soon" for at least two weeks before I open the downloads for everybody. In the meantime, you can add it to your wishlist
Have fun SuperTuxing!
~ Semphris