oh the power ups are one time use only... Thats really lame.
What i found addicting and cool about this game is the level up characteristic but this got shut down by me realising these perks are not perminate and only single use items.
What i reccomend doing is taking this in a scaleing direction. for example challenge #1/3 is you need to get 50 pixles in one run, then once you complete that its replaced by get 75 pixles in one run, and so on. I also recomend having more than 3 active tasks but have 3 tasks that are consistent and just harder than the last time Plus having some random tasks you can complete. The upgrades should cost more i guess but last forever.