Challenge two needs to be a tad bit easier. maybe individual bots losing health if that particular bot hasnt reached you in a while rather than if one single bot hits you all of their health stops falling. I can manage the 4 enemy bots but its near improbable with the speed that your little puppy moves.
If the player uses maxed out el fuego, 3 maxed out sonic bursts, 4 maxed out mini helpers, and maxed out nuclear reactor, in payload mode, the (1) payload will spin around the rocket messing with physics. My rocket sat at 1500 just spinning around the screen for a solid 4 minutes. I dont know if it happens with anything else in combination or at a different payload.
the reward spins never land on anything aside from the 3 coins in the upper right corner. so far ive had 10 spins and only 1 landed on the medal literally right on the line. its not really a spin to win something its a spin for a little bit of gold.
 "NGU IDLE"){kind=icon}
 "NoNoSparks: The Ark"){kind=icon}
 "Bot Arena 3"){kind=icon}
 "Learn to Fly 3"){kind=icon}
 "Realm Grinder"){kind=icon}
 "AdVenture Capitalist"){kind=icon}
 "The King of Towers"){kind=icon}
 "Idle."){kind=icon}
 "Lucky Tower"){kind=icon}
 "Toss the Turtle"){kind=icon}
You should find Gem Upgrades again in the Upgrades tab once you have enough gems and money :)