Heck yeah! Love this style of game, with the ability to grind out if you get stuck.
The connections aspect seems like it could be built into something really cool, but in its current implementation it needs restrictions to matter. There are a lot of directions you could take it! Maybe wires can't cross, or a limit of connections per gun, or a limit of total connections, including a way to connect upgrades together which changes what they both do...lots of possibilities!
In any case, the core game is definitely fun already, so awesome job! :)