Those 'secret' games are google search games, not so secret at all. Talk to chatgpt and ask it to explain it. They're pretty much impossible to block. They're sourced from common google sources so blocking those sources would break lots of normal google stuff like search itself and probably docs, sheets, etc.
The games are html games, and use common html blocks like <div> which can't be blocked cause the names (can) change with new deployments. They run completely in the browser, there's no server involved at all aside from loading the search page.
Those games are often derived from Google Doodles, which use the same tech. Essentially, you can't block them. There used to be a Workspace setting to block Google Doodles but thats been removed a while ago.
The only way to block the games is to block searching for it. But if you blocked 'snake', you'd block a whole lot more than just the Google game 'snake'.
PITB. Shrug.