I haven't been able to find any mentions on party size in the Numenera core book. What I want to know is the ideal size for a party and the practical maximum and minimum party sizes. Is it possible, for example, to play with 1 GM and 1 PC? Is it too unwieldy to play with more than 6 PC?
Please note my use of "ideal" and "practical" and "possible". I really want to know: can I GM for 2 people/1 people/7 people and still have it be fun?
ADDENDUM: After a couple of runs through the Beale of Boregal adventure, I can attest that the game is playable with only 1 PC. The biggest modification I had to make was to the intrusion system, because there was no other player with which to share the extra XP point. I houseruled that by giving 1 XP only.
Apart from that, I had very little combat happen, but the system was great fun to use 1 on 1.