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Real Steel World Robot Boxing provides fighting robots game.
This free Android app provides the opportunity to fight with robots. There are a lot of different robot models that can be unlocked. It's received thousands of downloads, showing how popular it is. It's supported in English and doesn't require a lot of storage on a device.
The main downside is that the robots have no personality. Ultimately, there are in-app purchases, so it's possible to get more tools and combat systems if you're willing to pay.
It's not the best game out there, but it is free and entertaining for a while.