In brief: Valve recently launched a tool that allows gamers to check the Steam Deck compatibility rating of every game in their library. Kotaku's Luke Plunkett, who has more games than any one person I know, recently check to see how many of his more than 800 games were compatible. The results might surprise you.
Plunkett has amassed a sizable collection of titles over the years - 810, to be precise - and decided to check his collection's compatibility as a bit of a real-world indicator to see how Valve has prepared for the handheld's pending release.
Many of the games were sent to him for evaluation for a review, meaning they span a variety of genres and eras.
Of the 810 games in his library, only 59 were fully certified and 100 percent ready for the Steam Deck. Additionally, 66 fell into the category of being functional, "but might require extra effort to interact with or configure."
Plunkett's collection consisted of just 23 games that flat out aren't compatible with the Steam Deck, including titles like Rage 2, Gears 5, Rainbow Six Siege and Surviving Mars.
The Steam back catalog is pretty massive, and this is an ongoing process, so if one of your games hasn't been tested yet, that doesn't mean it won't work well on the Steam Deck. Indeed, the remaining 632 games in Plunkett's collection fall into the untested category.
Valve notes that you'll be able to install any title in your library onto the Steam Deck, regardless of its compatibility rating.
Valve will start the Steam Deck purchase process on February 25, sending e-mails to the first batch of reservation holders. These people will have 72 hours to complete their purchase; fail to do so within this window, and Valve will release the reservation to the next person in the queue.