๐ช 0 coins
Every game pays out coins when it ends. Spend them here on upgrades and new looks.
You can have one upgrade per game (and level it up), or buy the bundle to get every upgrade at tier I. Switching to a different upgrade gives you half its coins back. Upgrades work in single-player games. They're switched off online and in the daily challenge, and leaderboard scores made with them are marked "boosted".
Looks are just for show, so they work everywhere. Only you see them.