Despite Steam Deck's shortcomings of one kind or another, its launch was a resounding success. There are already many games that are compatible with this handheld/console two-in-one device, but there are still a large number of games that are not compatible with this handheld for a variety of reasons.
Recently, according to the news released by Steam, Xbox Game Studios has confirmed the list of games that support and do not support the Steam Deck handheld. Including the "Verified" tab, the games that support SD handhelds are Italian Airliner 2, Hellblade: Xena's Sacrifice, Ninja Frog, and Max: Brother Curse.
The labels of Sea of Thieves, Forza Motorsport: Horizon 5, Forza Horizon 4, Quantum Break, and Rotting Nation are "Playable." This means that these games need to adjust the settings slightly to run.
Finally, Halo: Master Chief Collection, Gears of War 4, Halo: Infinity, and Microsoft Flight Simulator were flagged as "unsupported" due to the lack of anti-cheat support for these games.
But thankfully, Xbox Game Studios has entrusted the integration of SD handhelds for these games to independent studios, so the currently unsupported games may also be supported in the future, but in the short term, don't expect too much.