Hey, I actually built this exact same project (Nano, I2C SSD1306, LiPo, fits in a Tic-Tac box). I didn’t even try to get Arduboy games to run on it, though… the I2C display seems to have a much lower refresh rate than the SPI version. Also, the Arudoboy’s 32u4 has a bit more SRAM (2.5kb) than the Nano’s 328P (2kb).
And another minor problem: the buttons will have to be remapped as the 328P does not have PINE and PINF.
If your intent is to write your own games, these things won’t be an issue. On the other hand, if you just want to play other people’s games, it’s probably going to be quite a hassle and you might be better off just getting a Pro Micro (not Pro Mini!) and an SPI screen.