I like the core concept and the mechanics. I really think this game would benifit from a timer (Stopwatch or countdown depending on the mode) as I liked it more when I treated it as a Sonic game. Sometimes the slime felt redundant as you jump higher without it, while somewhat defeats the purpose unless the level design takes advantage of the mechanic, such as horizontal gaps or defeating enemies. Also, I would like to see how many slimes I have at a glance. This is a great concept. Good job!