What's a grand Android game for when you're on the go and need some quick, proper shooty action?

Seriously, Mech Arena has been an absolute godsend on some of these long train journeys across Europe. You can jump in for a quick match, blast a few robots, and then get back to planning your next stop. It's proper useful when you're bored in an airport too. What I really like is that it's not one of those games that sucks up all your data – which is key when you're bouncing around different countries and relying on dodgy Wi-Fi or expensive roaming. I've found it works perfectly whether I'm waiting for a bus in rural Thailand or killing time in a café in Berlin. Plus, all the different mechs and weapons keep things interesting, so you don't get bored after five minutes. It's just a solid, reliable game that always delivers a bit of fun, wherever you are in the world.