I guess TacOps 4 looks long in the tooth compared to much of the games market. However, the underlying playability is great and that keeps drawing me back, so a "son of TacOps" would go down quite well with me. Perhaps the fabled TacOps 5.
Slightly more seriously, the main things I'd be interested in are low hardware requirements, cross-platform, DRM-free (I increasingly dislike the current CMSF DRM), a 3d map with 2d contour visualisation, varying unit movement speeds and a better AI. But I'm going off-topic here.
Alternatively, I could go back to playing Die by the Sword which I recently (re)discovered....
Still play with it fairly regularly. Most of the time I use it, it is to answer/ask a tactical question, still love it. Really would love for a new version, or a patch to bring in the units added in the real world since its inception.