That's a good question.

I would think the first step is identifying the most likely candidate games for Nostrization.

For instance Imperials is FOSS and would only require new artwork. Something like Mario Kart is a lot less likely to be browser-based, but it's not out of the realm of possibilities.

I'd say it takes a lot.

I would expect the first Nostr game to be released by a company who is determined to keep producing Nostr games.