Nice
It was fun to do those acrobatic jumps, tho some backgrounds music would have been nice, and ability reset current map. Ball got stuck to those walls sometimes. Overall very nice.
Reviews for "Sling Jumper"
Good, but...
You are missing some selling points. You need music first, and sound effects. Music > boredom. SFX are important for many reasons.
Second, there's a few glitches: your walls aren't solid. I can go over or under them. In level 15 I went through the wall above the opening. Also, when I hit a sling going fast sideways, it bends alot (into a J) and then I just go through it. (Dunno...)
Suggestions: Level 11 seems to be too fast, may want to slow just a bit ( was hardest lvl 4 me ).
Speaking of slow, you may want to increase air control a bit. I get the point of less control, but the player will feel helpless and/or annoyed (two very bad things!). To counter the increased ease of that, you could add bounce to the sides of the screen or more traps/obstacles. If you do increase air control, cap the speed as you don't want them to be able to just bounce up and move.
!Highpoints!:
Fluidity, concept, and execution as far as gameplay were great! With a little work, this could be a hit, no lie. I did enjoy for the most part. I liked the way you started to design the levels and increase difficulty/technique, keep going.