[chii]

it depends on what the poster meant by "games" - do they mean engine and graphics? Or do they mean game design/mechanics?

Game engines and graphics is "solved" if you stick to popular concepts (which are those that are easily available in commercial engines).

Game design/mechanics is an unsolved problem imho - unless you consider it solved when merely taking an existing game design (like an FPS) and add nothing new to it (aka, those yearly COD military shooters).

Consider a game like https://store.steampowered.com/app/1141580/Taiji/ (inspired by the witness). This game is quite unique, and cannot really be recycled in to another game (without it being just a clone).