Konami and Evil Empire's Castlevania: Belmont's Curse is out on PC (Steam and Xbox PC), PS5, Xbox Series and Switch, and RPG Site tested the full PC version on several handhelds ahead of launch. The short version: Steam Deck struggles, while the Windows handhelds run it well once a couple of issues are sorted.
On Steam Deck, the game launches zoomed in with the sides cropped. Forcing 720p or 1080p and then setting the resolution in-game fixes that, but performance stays inconsistent. RPG Site tried both the stable and preview SteamOS channels and 15 Proton versions, including GE builds and Proton Experimental, and couldn't get it to feel good. Their recommendation for now is to wait for patches.
The ROG Ally launches to a black screen out of the box. The fix, from a Steam Community thread, is setting the refresh rate to 120Hz or lower in the quick access menu or Armoury Crate. After that, the Z1 Extreme Ally ran it at 60fps and up at 1080p in 25W mode, with 65-110fps in the areas tested. SMAA caused a few dips into the high 50s when the camera zooms out, and FXAA held up better.
Intel handhelds did even better. The MSI Claw 7 and 8 AI+ usually hit 90-120fps at 1080p at 30W, and over 60fps at 17W. The OneXPlayer 3 was almost locked at 144fps at its 35W max. RPG Site also suggests capping the frame rate with RTSS instead of the in-game limiter, which hurt frame times in their testing.