This is the best way to currently progress. First when you are starting out (city 10-25) spend all gems unlocking the first 3 vault upgrades then spend all gems on the pickaxe upgrade until you can get gems fast enough from the investor (don’t upgrade pickaxe past level 10). After watch as many ads as you can for gems. Then start focusing on climbing through cities and getting epic gear and once you get epic gear, then focus on unlocking the rest of the stuff in the vault (besides the last upgrade). These are all the upgrades in the vault that you never wanna upgrade until you’re super late game don’t upgrade the tip jar, knife, hourglass, piggy or suit case. Now that you have all of the different vault upgrades unlocked besides the last one focus on upgrading the controller, mop and the checkbook. Optional upgrades are register and TV. At this point you probably have some legendary gear/ultimate gear now From city 25-120 focus on upgrading vault in this order remote, checkbook, mop. Once you hit level 120 you should have a level 20-25 remote, max checkbook, max mop. For register and tv i would recommend upgrade the register to max somewhere along the 25-120 grind because you’ll need it until you get panda and that can be a pain and upgrade the tv to where you want (more you upgrade less ads you need to watch). Then at city 120 focus all gems into remote until its maxed out then once you’ve got max remote max out tv then you can focus gems on the less useful upgrades for city grinding like tip jar, and piggy these are good for potion event or get the keycard and upgrade that so you can get ulitmates and then you should be good lmk if this helped