Sierra isn't the most well known games developer. They now no longer exist due to being absorbed back into the parent company-Activision. Their two most recent games are Timeshift and World in Conflict. But you shouldn't judge a game by its developer.
This is a third person action game. You play as Glitch a robot created by rebel robots that are fighting mill robots controlled by the evil general Corrosive. The gameplay has quite a few different elements, platforming, shooting and puzzles. There are also some vehicles as well and a multiplayer mode.
At first glance this seems like a mediocre kid's action game but behind the cutesy graphics lies an intense shooter. The story isn't half bad either and some bits are rather amusing. This is a bonus considering that a game like this doesn't really need a story.
The weapons aren't anything special the usual lasers, machine guns etc. But with Glitch's tether gun you can control and possess your enemies this is great if you are up against massive robots or if you need to press a switch but can't access the area yourself. This makes a fun multiplayer mode where several bigger robots are situated throughout so you can take each other on as normal or with bigger more powerful robots.
Despite being an older rather overlooked Gamecube game I think that this is a real bargain. It's good for hardcore gamers as well as it is quite challenging.