скукотища — The game was turning out to be a borefest.

лучше: SNOOZEFEST

... or snorefest? Do they differ in degree?

No, just usage - I’ve never heard snorefest, I’ve only heard borefest once, and I hear snoozefest all the time.

It was seen in "Dictionary Of American Slang With Examples": A-Gee that movie was boring. B-Yeah, it was a snorefest! And can be found among synonyms to snore and snoozefest in Shorter Wiktionary.

Aha!