A bit late but I managed to do a 50-50 score for the theme slaughter (optimal strategy? low standards??) :D

Here are some of my ideas from my perennial 5-year-old spreadsheet of theme ideas which is going stronger by the minute.

Merge

A smith makes bronze, by merging copper and tin. One day he steals all your Tintin comics because it's twice as good as tin. Get it back. Also reality is merging with those comics.

Voyage, Paths or Transformation

You are one of those robot lawnmowers. Today, evil drones burn your yard. Now in the untamed countryside, you must cut crops for fuel, nettle for oxidizer, and drones for scrap. Use that to blast off to kill them. Bonus for otherwise minimal damage to nature.

Signals

You’re riding a bicycle and your weapon is stretched arm signals.