Rebirth · Board game rules
How do mission cards work in a 2 player game?
Quick answer
The rulebook doesn't specify different mission card rules for 2 players — Mission Cards work the same way regardless of player count in both Scotland and Ireland versions.
Details
In the Scotland version, Mission Cards are Private: you draw one by placing a Tile adjacent to a Cathedral space for the first time, keep it face-down and secret, and can satisfy its condition "even if you are tied with other players for the condition shown on the card" [p.4 — CATHEDRALS]. Since there are 8 Cathedral spaces, each player could gain up to 8 Mission Cards regardless of how many players are in the game [p.4 — CATHEDRALS]. These are revealed and scored at the end of the game [p.4 — FINAL SCORING].
In the Ireland version, Mission Cards are Public: 8 are dealt face-up above the board at setup, and any player can complete them during the game. The first player to complete a mission scores the higher value and places a Cathedral on the card; subsequent players who complete it score the lower value, with "any number of players" able to score the lower value [p.7 — PUBLIC MISSION CARDS]. This applies the same way in a 2-player game as in a 3- or 4-player game — the rules make no distinction based on player count.
Watch out: Don't confuse this with the Sprawling Settlement scoring in Ireland, which does have an explicit 2-player exception (the top two Influence scorers combine values) [p.7 — SPRAWLING SETTLEMENTS] — but no such exception exists for Mission Cards themselves.