The great thing about open-source games is that they’re free without caveats (unlike pretty much every kind of “free” game on the Play Store, which usually is littered with in-app purchases). The following list are some of the best ones you’ll find on Android.

1. Freeciv

This open-source iteration of Sid Meier’s legendary history-spanning saga, Civilization, has been in development for twenty-two years, originally coming out a month before Civilization II. Considering Freeciv and Civilization 2 share a similar isometric, pixellated perspective, we can deduce that Sid Meier actually copied Freeciv. Maybe that’s pushing it too far, but Freeciv is the purest, deepest Civ experience you’ll get on Android, allowing you to pick from dozens of nations, and lead them from tribal huts to soaring skyscrapers, and spears to stealth bombers. It may look old-hat, but it’s a far more Civvy Civ game than the superficial official mobile offerings from Firaxis.

2. Freedoom

The amount of longevity in the Doom engine is incredible, as proven by the immensely popular Brutal Doom series. A little less known is Freedoom, an open-source version of the game that makes some surface-level changes (different DoomGuy, redesigned monsters and levels) but crucially holds onto the demonically fast gameplay. The controls are fiddly by default but highly customizeable, so you can tweak it for a perfectly enjoyable variant on the classic Doom formula.

3. OpenTTD

Everyone growing up in the 90s remembers Transport Tycoon Deluxe, even if they didn’t necessarily play it. It was just there, on your dad’s computer or on the game store shelf in its chunky cardboard box. OpenTTD is an accurate open-source version of it, a deep simulator tasking you with managing transport – land, sea and sky – in various cities to ensure it’s safe and economically productive. There’s something infinitely appealing about those old-school graphics and the process of making a city tick along smoothly. The team have done a great job making it all run nicely on modern systems, as well as adding extras like HD graphics packs and multiplayer support for up to a whopping 256 people.

4. SuperTuxKart

There are a lot of Mario Kart ripoffs in the world, many of them on Android – the natural home of all things derivative and ripped-off. But until Nintendo releases the actual game on mobile (not impossible anymore), your best bet is the lovingly crafted SuperTuxKart. It’s hugely imaginative, with well designed tracks, colorful characters, and an array of weapons and vehicles that have echoes of Diddy Kong Racing about them. The game looks fantastic at the highest settings, with some glossy lighting effects and vibrant presentation, but if your phone struggles with it, you can always turn them down.

5. Dungeon Crawl Stone Soup

This one’s for the hardcore old-schoolers. The “Rogue-like” genre has been the rage in gaming for the past few years, but are you curious to know what an actual roguelike looks like? We’re talking ASCII graphics and text descriptions here, transporting you all the way back to 1980. Dungeon Crawl Stone Soup takes some getting used to, but once you master its abstractness, this is a riveting romp through dungeons of hashtags, full stops and all manner of symbols to decipher. It’s a game that you should at the very least play out of historical interest. And if you want to take the plunge with friends, there’s a multiplayer version, too!

Conclusion

You’ve probably noticed that many of the above games are based on oldies, but that’s part of the beauty. Where most mobile developers aim for quick-fix simplicity, this open-source trove shows that it’s perfectly viable to have more complex games on Android, too. As they’re completely free, there’s no harm in trying, right?