Say plainly that there is no player limit, and stop one classroom hitting it

The README heading read 'Two people, two browsers', which sounds like a
cap. It is not one: the server holds no game state at all, so any number
of people play independent games and the server only ever sees a
finished score. The only real cap is four to a game, and that is a
keyboard sharing the same stand rather than anything technical.

Checking that turned up a case where it would not have been true. A
classroom, an office or a household all arrive from one address, and the
submission limit of thirty an hour was low enough that a class finishing
together would have started losing scores to a 429. Raised to 120 and
verified with a burst of 130: the first 120 land, the rest are refused.
What actually keeps rubbish off the board is the plausibility check, not
this limit.

server/README.md

@@ -25,9 +25,10 @@ Everything in a request is treated as hostile. Names are forced to a printable
 uppercase subset and cut to 12 characters. Every number must be an integer in
 range, and a score is refused if it could not have happened: assets above
 `$2.00 + $25 a day`, or glasses above 400 a day, are rejected as impossible for
-the days claimed. Bodies are capped at 4 KB and submissions at 30 an hour per
+the days claimed. Bodies are capped at 4 KB and submissions at 120 an hour per
 address, which is why `TRUST_PROXY=1` matters behind nginx — otherwise every
-request looks like it came from the proxy.
+request looks like it came from the proxy and one busy classroom would lock
+everyone else out.
 
 **It cannot prove a score is real.** There are no accounts and no signing, so
 anyone willing to craft a request can post a plausible score under any name.

server/src/index.ts

@@ -53,7 +53,14 @@ interface Bucket {
 }
 const posts = new Map<string, Bucket>()
 const POST_WINDOW_MS = 60 * 60 * 1000
-const POST_LIMIT = 30
+/*
+ * Per address, per hour. Generous on purpose: a classroom, an office or a
+ * household all arrive from one address, and thirty was low enough that a
+ * class finishing a season together would have started losing scores to a
+ * 429. What actually keeps rubbish off the board is the plausibility check
+ * in validate.ts, not this - this only stops the database being hammered.
+ */
+const POST_LIMIT = 120
 
 function overPostLimit(ip: string): boolean {
   const now = Date.now()