If 40K is a game too far how about:
 
"XENOS RAMPANT: BY RICHARD COWEN & DANIEL MERSEY
We are delighted to announce that we’ve signed a contract with Osprey Publishing to produce the next book in the Rampant wargaming series: Xenos Rampant.
Xenos Rampant is a set of miniature wargaming rules for fighting science fiction battles for fun, free of adherence to specific model ranges, canonical settings or ever-expanding supplements. Armies are typically composed of around 30-50 models. Most players prefer to field 28mm models, although other scales are just as playable.
Xenos Rampant is a completely standalone set of rules, but retains the simplicity, feel, and ease of play of Lion Rampant. Richard originally built Xenos Rampant as an unofficial variant based on Daniel’s Origins-nominated system, and we have worked together to develop the idea. The basic rules should be familiar to players of Lion Rampant, although the very different nature of futuristic warfare has necessitated some changes to the rules.
Xenos Rampant will be published as a hardback book by Osprey Publishing in 2022."
 
Cheers