Looking at my "competition" and what's on the market right now, there are two major Arduino handheld gaming platforms at the moment of writing, that pop out

if you want to get one cheap, here's a link to their current kickstarter - special editions are already gone, but you can still get a standard version cheaper then everywhere else. (https://www.kickstarter.com/projects/903888394/arduventure-on-arduboy)

PROs 

• resolution of 128x64 on an OLED is bigger (although 1.3 inch seems a bit small, the overall design is looks great)
• bigger community than Gamebuino
• rocks a transparent injection mold case

CONs

• no SD card support (there's a kickstarter for GAME BYTE, a clone that features that though https://www.kickstarter.com/projects/1276403687/game-byte)
• no external pins 

PROs

• SD card support for having a lot of hex files and games
• I2C and serial connection pins have headers 

CONs

• although I chose the display myself, it's notable that 84x48 pixels is less than 128x64 pixels 

There is a 1.54 inch OLED display, that seems reasonable in price to work with and maybe switch to the ESP32 to make it slightly easier to deal with buttons etc. - although I'm not sure what that means for deauther support (I think that's only possible with the ESP8266 right now, correct me if I'm wrong). But I'm pretty happy with the state of the project (except for sound, but I2C soundcard is coming https://playground.arduino.cc/Main/SIDuinoI2c - thank you @Radomir Dopieralski  ) and I will continue to make this a small run thing for tindie.