Introducing with Update 0.4 "It's a Bargain!": The Super Secret Secret Shop!
If lucky and persistent enough, you can now find the portals on levels of Moss Destruction which will teleport you straight to the merchant of exotic wares.
Here you will find 3 items picked randomly from a pool of many. These can be cartridges you can install into your mech to influence the gameplay for your benefits. You can find yellow, Global cartridges, which - once bought - will activate and grant a certain bonus or modification for you in all the runs that follow. You will also find blue Passive and red Active cartridges here. These can be installed into your mech before each run and depending on your choice of selection will change the gameplay accordingly for that run only. Selected Passive cartridges will do their magic on their own, no need to interfere, while selected Active cartridges can be activated by you during the run. These will most likely have a cooldown on them after each use.
Another thing you will find in the shop are new Mech Tech cards and Upgrade cards for existing Mech Tech already in your possession. If bought, these will automatically be shuffled into your mech tech deck from which you can randomly pick from with each new rank in the game. Last but not least you will find new heroes you can buy at the merchant. Once unlocked, these heroes and their corresponding mechs will be available to pick at the beginning of runs.
Unlock as many of these as you can to find the modifiers and characters that suit your playstyle best!
Collect Krysol scattered around the maps to spend at the shop. You can also get more Krysol from some enemies killed, for completing special actions and combos. Note that while lingering around in levels after sunset is potentially more dangerous, it will also cause enemies to drop Krysol much more frequently! All Krysol you collect throughout runs will stay with you even after death. Keep collecting Krysol to boost your mech and overcome previously difficult challenges more easily next time!