It's a cute game and I had fun playing! My feedback would be that the main mechanic seemed redundant/without impact esp. for speed witch starts at 50. Also I would suggest favouring the positive upgrades over the negative ones since humans usually remember negative things longer and can't estimate their chances unbiased. So maybe display 50/50 but actually do 60/40 or even more. Helps with players not getting frustrated thinking they are on a loosing streak.