Re-tar ground to make money and buy upgrades. Press Space to activate tarring, and S to open the shop. (The lag is because of it checking how much you've done so far.)
Credit to @TPS1001_Games for the color sensor I used for checking if you've tarred enough: https://scratch.mit.edu/projects/540523905/ Credit to @MJ26595 for the money counter in the shop: https://scratch.mit.edu/projects/490136981/ And finally, credit to @rhlp for original idea for the tar spreader game. Grond