Pokémon Blue on Gameboy Color.
Update (05/30/2020):
My game boy color went missing after I upgraded to a clear case (The buttons were sticking). Replacement costs 9K$ new from eBay. Ordered two knockoff replacement units from Amazon.com for $199 each, instead. FML.
After the replacements arrived, I found the missing OG Repaired GBC in the kitchen cutlery drawer. FMLx2.