I like RPI for you. They have an extremely quantitative (modeling and game theory focused) econ department in addition to top-notch CS and math. It’s a highly rigorous school but not one where a blemish or two on your transcript is going to sink your application, especially given the very high (and STEM-focused) rigor of your courseload. Hopefully you could get some merit aid. You would find tons of competitive gamers there, as well as students who would share your academic passions.
The blended CS-econ programs at MIT and Brown look amazing, but those are not only tough admits but also zero-merit-aid, high-sticker-price private U’s. It seems to me that RPI hits the sweet spot - every bit as rigorous, but with the possibility of merit money on top of what I think would be a likely admit.
Also with merit aid potential: https://www.wpi.edu/academics/study/economic-science-bs
NYU also has a CS+Econ track in its CS Honors program
BU and Brandeis could be worth a look as well. (Also Tufts, but no merit $ there.)
And Rice: https://economics.rice.edu/undergraduate-program/mathematical-economic-analysis-major (and very strong CS also… and “sticker price” for Rice is not much worse than OOS students pay for the UC’s.)