Step 1 (If you are smart) Patch a Roblox client, Set it up with clientargs, and done!

Step 2 (Lazy but still smart) Modify 2011M so it loads with [Whatever client year you want] coregui scripts

Step 3 (Lazy and knows nothing about these clients things) Just get a Roblox studio and hope it will work with play solo, That's it lol

what is client args?

there should be a step 4: wait until the client comes