There will be no exclusive games for the Steam Deck
The Steam Deck, which has been delayed until next year; will allow play practically the entire Steam library in portable mode. It is a personal computer with its own screen, emulating portable consoles, which will allow us to access the entire Steam catalog, and we will even be able to install everything we want on it because, after all, it is a PC.
What benefits will there be for the Steam Deck? Well, we know that all Steam games so far will work with few exceptions, and that you will be able to play the games on public transport due to their portability. But one thing that is known that the Steam Deck will not have, will be the exclusive games.
There will be no games that will only work on Steam Deck
Valve is betting big on the Steam Deck, which has generated a lot of interest from developers and fans. Although it will have many guaranteed sales from users who have a large library or who want to get into Steam, but feel that setting up a PC is complicated, Valve has confirmed that at least they, will not publish any games made exclusively for the Steam Deck.
As part of the Steam Deck FAQ page, Valve addressed the idea of the Steam Deck offering any games They responded by saying that making exclusive games doesn't make much sense for them, because "the Steam Deck is a PC and should play like a PC«.
Kitguru speculates that mobile game ports may be possible, taking advantage of the fact that Steam Deck has a touch screen. That would be a possibility, but it would be by developers outside of Valve, which would also have to send the game and be approved. However, with the way Valve is marketing the Steam Deck, it makes sense for the handheld to position itself as an extension of PC gaming, not a separate market.
Source: Kitguru