Android



Google's Android used to be the "other" phone & tablet operating system, but its market share has since skyrocketed far above Apple's iOS. Commercial developers still tend to prefer Apple, as its users seem to have more disposable income, but indie and emulator developers have flocked to Android because it is much less locked down (yarr!). So it's basically PC mustard race, for phones. Speaking of which, it is possible to run it on your regular computer too, with Android x86 (installed, or as a live CD, or under VirtualBox). Or you can use BlueStacks.

Get your apps from here:
 * Google Play Store - Default "app store" that every 'droid phone should have
 * AppBrain - An alternative way of browsing the apps available on Google Play
 * SlideME marketplace - Download emulation apps from here
 * UpToDown - A free apk repository
 * F-Droid - A catalogue of Android free/open source apps

Some emulation apps are available at the SlideME marketplace, some are on the Google Play Store!

Protip: If you're buying from Google Play, you've got a 15 minute grace period to return the app. After you buy it, if you go back to the Google Play page on your device, you'll have a 'refund' button. Great for if you're getting buyer's remorse in the first 15 minutes.

Protip 2: If your cellphone experiences random framerate drops and stutters, activate flight mode and enjoy your superior performance.

Protip 3: Understand the limits of your device! This should be obvious, but it must be stressed, given the immense variety of Android systems. For example, it will be hard to run high-end games or a PS1 emulator at full speed on a single-core 800MHz CPU. If you want to play anything serious, your device should be as powerful as a Google Nexus 7. (it's $200, get one)

Free games
If a game is free to install, but pay-for-play, it goes in the other list. If the game has a free version or demo that's good enough you'd play it without ever buying the full version, it goes here.

Commercial games
Stuff that you pay to download, or subscribe to play online.

Note: If you really don't give a fuck about the developers who made these great games, you could just google the name of the game and add apk at the end, and you'll almost always find an apk file from some site like apkmania, then just install it on your phone. Only works for games that AREN'T subscribe to play online. (Really though, if you enjoy one of these games and play it all the time, spare a few bucks and buy it from the store)

Emulators
Just install and play the games of yesteryear directly on your phone! Also, did I mention that there's no rooting required for these apps to work?

Root required
1337 hackers only