Some games age like fine wine, which is why retro gaming is so popular. In fact, if you want to play games that are 10, 20, or even 30 years old, there are plenty of options on PC and console. If you want to play them on the go, however, those options significantly narrow.
It's practically impossible to talk about classic gaming without talking about emulation, and that's the case here. Half of these gaming handhelds are "legitimate," in that they have commercial software ecosystems and use video game cards, cartridges, or official downloads to function. They're still technically emulation-based; in many cases, they use older game roms and emulators that mimic those games' native systems to run on modern hardware (though there are some cases of classic games being completely ported).
The other featured gaming handhelds are open, emulation-based devices. That means you're on your own to find retro games to play. Roms are a legal gray area, so we can't point you in a direction to find them besides "back up your purchased physical games, if you have the hardware to do so."
Commercial gaming handhelds with their own ecosystems are pretty rare, and will probably remain so as long as Nintendo dominates the portable game console market and Microsoft and Sony focus entirely on home hardware (though it would be nice to see a Vita 2 some day).
Completely open, emulation-based handhelds are another story. You can find dozens of different Linux- and Android-based gaming handhelds, most of which originate in China, on sites like AliExpress. The two on this list are just a sampling of the many retro gaming handhelds that you can buy, but they're among the most well-made in the category.
If you prefer to play classic games on your PC, check out our guide to the best emulators. And if you want to play old-school games on your TV, read up on the best retro gaming consoles.
The original Nintendo Switch is an amazing game system that works as a home console when connected your TV or as a handheld when removed from its dock. The Nintendo Switch Lite takes the Switch's power and game library, removes the home console functionality, and cuts $100 off the price. If you pair it with Nintendo Switch Online ($20 per year), you get dozens of NES and Super NES games to play on the system—and that's only the start. You can also buy many classic Nintendo and Sega arcade titles, and nearly every Neo Geo game ever made.
Technically, most Switch games are emulated in some form; you just can't load your own roms (wherever you may find them). They're being emulated "legitimately," with each game (or game collection) supplied by the license holder. So, while emulation is a factor, it isn't nearly the dark, gray area associated with the open, emulation-focused handhelds below.
The Anbernic RG351P is a Linux-based, emulation handheld, but don't let that put you off. It's surprisingly easy to get games (up to the original PlayStation) to appear in the system's interface; you simply drag and drop games into system folders. It's just as simple to completely overhaul the interface with a handful of third-party, customizable loaders. The system also has a good build, and an ideal screen for Game Boy Advance games. The Anbernic RG351P is one of the most accessible, emulation-based, retro gaming handhelds we've seen so far.
Getting "legitimate" copies of games to put on the system is another story. Some system versions come pre-loaded with legally dubious rom libraries. If you want to add your own games, though, you'll have to find your own ways to acquire them.
Evercade
Evercade is a fascinating handheld so old school that it still uses cartridges. At $20 a pop, each game card comes with a collection of classic games (and obscure gems) from various publishers, including Atari, Data East, Namco, and Technos. As a bonus, Evercade has HDMI-out, so you can connect it to your TV.
Technically speaking, the Evercade is an emulation-based system. The game roms are simply stored on the cartridges rather than in the system's storage, and to play them, the Evercade emulates numerous older platforms. Like the Nintendo Switch's retro titles, these games and collections are legal and legitimate, since they're authorized by the publishers that own them.
The Retroid Pocket 2 is a powerful, emulation-based system that runs on Android. It can handle games up to the Nintendo 64 and PlayStation (and even some PlayStation Portable games), and looks and feels great.
The only drawback is the Android interface, which is clunky without a touch screen (you use the analog sticks to navigate). You can install different UIs on top of Android to make the game selection process smoother, but it's a fair bit of work to do. As with the Anbernic, building a Retroid Pocket 2 game library is something that you must do on your own without our assistance.