Inspect robot parts
Start with the assembly system. No optimal part combination is established by the source. [1]
Compare activities
Use the descriptions of floors, bosses and the Junkyard to understand the combat and scrap-collection activities. [1]
Read upgrade and rebirth prompts
Both are listed systems. Confirm their current costs and reset effects inside the game before committing resources. [1]
Keep Cash and Scrap separate
Use Cash for the robot-part purchases described by the developer and Scrap for robot upgrades. Check the amount displayed in a resource pack because the catalog says it scales with prior earnings. [4]
This guide summarizes the linked sources; it has not been tested in-game.