We are starting an Star Wars: Imperial Assault campaign and one member of our group is not "always available". Will this be a problem? Do the rules support this and will it unbalance the game if the number of players varies between sessions?
It shouldn't be a problem as long as you guys are willing to share control of that player's character when he isn't available or are OK with taking some risk with game balance by having the number of players vary between missions.
The number of players in the game does matter and is meant to be fixed. The campaign setup (Rules Reference Guide, Page 7) requires that each player choose a Hero and handles assignment of the Legendary/Heroic cards for games with less than 4 players at campaign start time. If the number of players changes, you'll need to add/remove Legendary/Heroic cards as appropriate.
Campaign setup also affects the building of the side mission deck (Rules Reference Guide, Page 17) as each hero's red Side Mission card will be inserted into the deck.
Critically, the number of credits granted at the end of each session scales based on the number of players. The game wasn't designed for this to vary.
You likely could change the number of players between missions, temporarily removing their side quest and granting less credits at the end, but this means that the pool of players will have less credits than they ordinarily would have had. This can be fairly impactful, as it's a common practice to pool resources to load up one or two heroes with great end-game weapons and attachments. Additionally, the missing hero would either need to be granted XP upon rejoining the game or fall behind.
There are also some logistics to consider: if you have the missing player's hero controlled by the group, you may want to coordinate which abilities they would want to pick if you're doing more than one mission at a time.
I personally feel it's best to just control that player's character in their absence to keep the number of players constant. Some groups will opt to always play with four heroes, even if there are less players, as some missions feel more balanced with a full group and support characters get a greater chance to shine.
The game is designed to be played with a constant number of players. That said, it is absolutely possible to change the number between plays, with a few caveats.
The Imperial player should be able to attend every session
One player plays the Imperial side throughout all missions. However, they have several choices that remain secret from the other players until revealed, such as purchasing special cards to play. If the Imperial player can't attend your session, you can have another player take their place, but that will result in them finding out any of these secret cards. I think that these are minor spoilers though, and some play groups are okay rotating who plays it.
That said, during a particular scenario, the Imperial player has a substantial amount of information that needs to be kept secret from the players, so I do not recommend someone trying to play both sides.
Rebel players are supposed to remain constant…
The game is designed to have the same number of Rebel players each game. If you are playing with fewer than four players, the remaining characters receive special benefits to become more powerful. The credit allotment at the end of each mission is per player as well.
Given this, the recommended solution for what to do when you are missing someone is to have a Rebel player play their character and the missing one. That way, the game functions the same way as if everybody was present
…but we successfully played a campaign where we varied the player count
In our campaign, we just did the following:
- During each scenario, give out the special cards for playing fewer than 4 players if we are missing somebody
- If somebody is missing, allow their gear to be distributed to other players
- Always reward the team with credits as if we had the full number of players
The reason we gave full credits even if we didn't have a full number of players was because we didn't want the Rebels to be underpowered when everybody was at the table. This probably meant that the Rebels were slightly overpowered when somebody was missing, as the team had more gear than they would have had normally.
An alternative that might be fairer is to not allow the missing player's gear to be used by other players, or to only allow a few items associated with the player to be used. At any rate, I believe it is definitely possible to play with missing players from time to time.