If you loved FEAR or the newer Wolfenstein games like I did, you'll likely enjoy Selaco too. It takes after those games the most (and even bits of other 2000s FPSs like Half-Life 2) despite getting labelled as a "boomer shooter", being chock-full of secrets/references and running on GZDoom.
The base price of 25 USD might seem a bit steep for an indie title and the game is still in EA, but this is the rare case where you'll get your money's worth in my opinion. The now-released first act (pre-update) is clearly an indicator that the overall design, gameplay loop and vision for the game has been nailed down to a T even if they still semi-regularly update it to tweak it further. From the updates, it also seems they actually have a plan for the next two acts to be released by this century (2025 and 2026 respectively).
That all being said, the story elements (beyond visual story-telling and logs/emails) have been left out for now and there's a big story update coming in by the end of the year so you can also hold off until then.
:dawn-salute:
As someone who's also a fan of SS (both of them), Selaco does have a lot of ImSim elements even if it isn't one itself.