As The Gadget, you turn in criminals for cash which you use to upgrade your gear and you fight for XP which you can use to train in the standard attributes (fighting skill, strength, intelligence, endurance, speed).
Your gear is upgraded along many tiers in pseudo-scientific disciplines, such as Explosives (traps and bombs), Chemistry (gases and poisons), Electricity (ranged attacks and electrical control), Ballistics (guns and knives), and Pneumatics (exoskeletons and other devices like a grappling gun), which constitutes the main focus of the game.
The Gadget plays like a sandbox game, so you're free to build up a network of contacts and informants who give you missions once you do certain favors for them. There'd also be a small investigative component, enough to satisfy gamers who like solving puzzles but not enough to detract from the action-oriented flow of the game. A multiplayer mode is unlocked after you accomplish certain objectives, and it allows you to build up a character in advance and take on people with similar interests (eg, people who mostly play king of the hill or only play deathmatch) and similar skill levels (time played and win/loss records).
The story revolves around the Gadget making the streets a safer place first by cracking down on protection rackets and other criminals, then by addressing white-collar crime that traditional supers aren't equipped to handle, taking care of corruption in the metas, cracking a serial murder case, and finally facing off with a dangerous mutant which evolves in response to the gadgets you create.