This is the first game that completely freezes on my S&Box console, and the only solution is closing programs through the task manager. I don't quite understand why no one mentions this in the negative reviews.
All upgrades in the game are one-time use and must be repurchased after death. Simply put, the player needs to make a few unsuccessful runs, farm, buy the maximum upgrade, make a full run, and then repeat if they lose.
BUT there's a big "but." It's more profitable to simply get hit by flying objects and gain experience and levels simply for losing, since flying in any direction grants experience just like in a normal game, but due to the acceleration from being knocked back, the character flies much faster than simply running, and therefore gains significantly more experience.
You can also fly onto the trash heap itself, which is the starting location. At the top, you can easily run endlessly and gain experience just as endlessly.
If you have enough patience, you can use this method and simply get all the achievements and level up your character to level 100, provided that the game does not freeze.