depends on the definition of gimmick. it's a "gimmick" because the VR experience is 95% of the reason for playing a VR game. I've tried a fair amount of VR games, and while beatsaber is great, it's just DDR bro. and that brings me to another example, in this sense, the interactive aspect of DDR could be seen as a gimmick too. it's just a game with arrows that fall down the screen. I wouldnt have played that game at all without the physical aspect because there's just not much else there. and while that's fine, my worry with VR, at least during the early stages, is that the games will have a poor narrative with boring mechanics, simply because the main focus of the game is the VR. and while those things could only improve the VR experience, will these new, trailblazing games like half-life really focus enough on the other tenets of a video game? only time will tell.
but honestly, even with those things aside, half-life just doesn't feel like a VR game. I want to shoot at things and jump around with source movement. maybe that's the boomer in me tho