Is it permissible to buy and play games on platforms (Steam, PlayStation) or games that are multi-game hubs (Roblox) that host haram/blasphemous content (mocking Islam, depicting 'Isa peace be upon him)? No platform is 100% void of haram and can't find/don't know ones that doesn't have that.

Ustadh AbdulAziz al-Haqqan

Take it as a rule: a game is judged by what it itself contains, not by everything else the platform happens to sell. What you really need to be tackling is your waswas as this type of thinking is not healthy for you.