Are there an infinite number of sequal BOX QUEST games?
There is no max.
The code just checks if you're level 100 (data.level.value >= 100), if you can pay 101 levels (new Cost(data.level,101)), and if your anticipation is infinity (data.anticipation.value >= 1e51).
Then it calls Ascend() which just adds one to your "ascension" (window.localStorage["ascension"] = JSON.stringify(ascensionlevel + 1)).
Then the next thing is you buy "BOX QUEST " + F(ascensionlevel).
You can keep going as long as your patience allows.