How about a Shadowrun style sandbox game set in a run-down sleazy dystopia, using the proc gen city tech they've already developed. Make the style lower poly like Unreal engine 3. That looks nice but it's a lot less work to develop assets for and you can run it on a potato. People don't really care about graphics in indie games. What matters is gameplay and innovation.
The setting has endless potential. There could be biomes like the slums, abandoned wasteland, industrial area, etc. You could manage a gang and choose what to specialize in, such as hacking/infiltration, security/bodyguarding, or ghoul/supernatural creature extermination. Then take over territory, fight other gangs and corps, do proc gen missions, respond to attacks from other organizations, amass your funds and resources, and take over the city. Endgame could be an endless fight for power against another super powerful competing megacorp. It could be kind of like Kenshi but more exciting and more accessible.
I really hope they're working on something we haven't seen before. I'd be disappointed if it turned out to be following current trends or be set in the same European forest we've seen 1000 times already.