I'd recommend the standard 3-5 players in a crew. Solo play would be very hard to survive but I'd love to see how well a creative character could do! The game is procedurally generated as you play so there's no set difficulty or a point that would definitely be too hard or too easy. If I was a player in a smaller groups, I'd play quiet and smart and try to forge an alliance with another team (but who knows when they might turn on you?!).