the game seems fun, though mapping midair jump to left and right means you basically have to commit with the momentum of the starting jump, as istinctively trying to adjust midair will result in wasting extra jumps and your subsequent death.
you can get used to it after a while, but it would be nice if you could at least choose between different control schemes given there's an objective for clearing the entire game with no deaths (on that note, is the only way to reset your death count refreshing the page?)
having a button mapped to level reset that doesn't require to go through the menu every time would also be welcome.
edit: it may be worth considering giving each level its own separate death count for the purpose of the medal, and the total death count would be the total sum for each level (not sure how the leaderboard works, so can't tell how it would affect that).
i'm saying this because it would be very difficult to complete a full deathless run in one sitting, and it's currently possible to cheese the deathless medal by clearing the game, refreshing the page, then going to the last level via level select and clearing that alone with zero deaths.
adding separate death counts would ensure it's not possible to cheese the medals, as you would still need to clear every level with no deaths, while also making it more forgiving than having to go through the entire game in a single sitting