Throwing out an idea for a game jam: set a limit on how much power (wattage) the game may consume when you play it. I mean total of CPU, RAM and GPU. There are software out there to measure this (the info is even available in task-manager on Windows and process analyzer on MacOS). Prove you meet the restriction by posting a screenshot of power consumption of for example MS Word (or equivalent) and your game.

What do you think?

I like the concept idea, but i think it would not work. At least not like that. It is drastically individually different  for the platfrom the game would run on.

A PC can take about 20-100 Watts without doing anything at all and up to like 700 when doing stuff. Compared to a mobile device running 3d games with 5 Watt on slow charger. Worse, older cpu do not benefit from idle nops, they literally take as much power with or without computing. And you can run the same cpu with slightly higher or lower voltage or just flat out let it run slower to save power.

Is there  maybe a debug tool to measure flops or some metric like that? I believe there are runtime analsysis tools to find bottlenecks and optimize.  

The ram could be measured easily, I guess.