This is a short explanation of the only title with a really easy — and the only — puzzle. Only possible on PC.
Heads-up before you start: the code you need is different for every player and every server. Don't try to copy a code from someone else's screenshot — it won't work for you.
Stage 1 — get the code, unlock the menu
Steps
Press the F9 key on PC, or type /console in chat.
You'll see a string of numbers alongside a "client loaded" message. Keep this code — you need it in a moment.
If the console is spammed with errors instead:
Rejoin the game and quickly press F9 again, then disable the Error checkmark. The window is small — if you miss it, rejoin and try once more.
Go to ⚙ Settings → View Other Options, then click the ??? button.
You'll be prompted with "ENTER CODE" alongside a textbox. Type or paste your string of numbers in there.
Press Enter.
Quirk: if you click off the textbox and click back into it, the contents are deleted.
Cancel behaviour: pressing cancel instead of entering a code brings up another prompt that just says Error with a regular cancel button. It's harmless but doesn't progress.
Success state: after entering the code and pressing Enter, you'll land at a SUCCESS prompt with a guide to the controls of the place you're about to be teleported to — and the entire environment goes dark.
→ At this exact point you also receive the "Neon" plot skin. You can stop here if that's all you wanted.
Stage 2 — get the title
Steps
After Stage 1 you'll be teleported to one of two dark rooms:
➊ Dark room with three yellow things
Walk into one of the yellow things. Only one of them will actually "crash" the game.
➋ Dark room with wedge, sphere, cylinder, and a long tunnel with a thingamasilly at the end(yes, an OWATAMSATE reference) Don't go down the tunnel. Find the cylinder and walk into it — it crashes the game, same as the yellow thing in ➊.
Result: the "crash" + Stage 1 path is what awards the Error title.
Related unlocks from this same path
Same puzzle, different outcome
Neon plot skin — awarded at the end of Stage 1 only (no Stage 2 needed).
Error title — awarded at the end of Stage 1 + Stage 2 (either room works).
Secret 6 badge — awarded by going to room ➋ and walking down the tunnel to the thingamasilly at the end. This is a different outcome from the cylinder crash, so you don't get both from the same walkthrough.
Note: the community-reported writeups for this title sometimes disagree on the exact sequence. If a step doesn't behave as described, rejoin the game and try again — the puzzle logic is server-side and a brief disconnect can re-roll the destination room.