I would love to know how you do it!

I usually begin by googling up the theme and watching pictures related to it. Yes, depending on the theme it can be hilarious or disturbing, but that's also inspiring. Google, Pinterest, Instagram, Twitter, Youtube... whatever. The more the merrier. Jot things down meanwhile.

Then I usually take a piece of paper and bein drawing a mindmap - you know, the theme written in a bubble in the middle, then nodes coming out from it with different ideas for stories, mechanics, feelings, whatever. I write anything that comes to my mind. IF I already have a genre in mind, perfect. But it I don't? Well, this step can take longer.

Finally I pick two or three promissing ideas and draw a mockup, see how they could look like, expand them a little bit, and 'roleplay' how it would play. The best one wins.

What about you? Do you use some proven method to come up with ideas you find interesting to work with?