A neat little cross between a platformer and a racing game. Absolutely wouldn't recommend at its normal price, but if you can find it on sale for $1-$2, it's a good deal.

Gameplay:
Defunct sees you playing as a robot with a big wheel as its only form of locomotion. You're on a race to catch up with a ship that's left you behind. Your engine is broken so you'll be using momentum to traverse the landscapes you come across. There's a bit of a learning curve to the controls. You hold down a button while going down slopes to activate a downward gravitational force and build speed, and release the button when going uphill or else drastically slow down. It's pretty tricky to start getting it right, but a lot of things can be done with this mechanic and it's satisfying to get good at.

Levels consist of wide open yet semi-linear paths through scenic locations. Some focus solely on speeding through the environment while others have you stop for a moment and activate some things in an area before moving forward. Every level is a decent length and there's a good amount of variety between them. Replayability is encouraged through multiple paths, hidden collectibles, and time trials. There's also a few side levels that'll really test your skills.

Visuals:
The graphics are kind of mixed bag. Overall, they're not super detailed and kind of look like they came straight from a PS2 game. It's a well stylized look though and is far from ugly. The environments are especially lovely and have a nice sense of atmosphere. The animation in the cutscenes was definitely not polished though, as things noticeably clipped into each other. This especially gave me a terrible first impression of the game.

Conclusion:
As said before, it's a good game to get for cheap. It'll take you about an hour to complete the main story, and there's a healthy amount of optional content to be explored. I'd recommend this game if you enjoy fast-paced stuff with high skill ceilings, like Sonic games.