Shift4k 0v3
Cursors keys to move, space is an alternative jump, and shift does... well, you'll see. Core game mechanic shamelessly ripped off from the Shift series by ArmorGames. The final version is intended to have 6 levels, but the 6th one will only be accessible by collecting the letters BONUS in the first five. This is intended to be hard: if you don't struggle to collect the U and don't consider yourself a hard-core gamer then please let me know that it needs to be more difficult...
There are some known bugs. I've tried to work around them with level design, but let me know if you run into any. Note that I consider getting completely stuck (unable to get anywhere useful and forced to find a spike or press Esc to suicide) to be a bug in the level design, and would appreciate a screenshot if you manage it. If you find a way to skip past parts of levels, I would like to hear about that too.
If a key gets stuck, ensure that the applet has focus and press the key again. This should unstick it.