I recently moved into a student housing complex and the power here is rather expensive and being a student I want to save as much as I can on power. So in an ITX framework I want to try and squeeze as much power in to 250 watts as possible, of course anything under that is a huge plus, 200 watts would be a cool stretch but I think then it's just becoming impractical. I'm mostly playing fairly easy stuff like KSP, CS:GO, and indie games, but I do play some demanding titles like GTA V, BF1, and Dishonored 2. But that said, I don't mind turning settings down to medium if it can save some money and power.
I'm asking here having done fairly minimal research because I honestly don't know where to start, the system will probably end up being ITX or Mini-ITX just because those motherboards generally consume little power (And I like small cases) but from there I don't know where to go. I already have an efficient 1080p monitor and peripherals and I've adjusted for them already. I also have a Samsung 850 Evo 500GB SSD from an old build so I have some storage, but would probably like something a little larger if it's possible (totally fine if it's not though).
Any recommendations for any parts (or how to best go about finding parts) would be awesome and very much appreciated. Thanks for reading.