So it's the GM and one player. Would you change anything about the rules? The social systems, combat initiative, Destiny Points, etc?

I throw with 2 Force Dice at the start, so the Destiny Pool is not just 1 LP sitting in front of the player waiting for the opportunity. Otherwise, I haven't changed anything ruleswise. Obviously the challenges scaled differently for 1 player with 1 skill set, but NPCs handling the specialist work if the need arises.

I've run for my son quite a bit. We always use 3 DP so there's some flow, plus there are too many situations where players could want to use a DP one turn after another, but with only 1 DP that's impossible if I don't also flip one immediately.

Conflict is a lot tougher to scale. Any string of cold dice can put the lone PC in serious jeopardy, so you always have to have a backup plan (capture & escape, Coruscant free-falls that land on passing speeders (or snagged by a large predatory bird), the arrival of "cavalry", etc). My first campaign I knew it would be an issue, so I gave him a droid sidekick which he also controlled. I also introduced a friendly NPC ally, but he started to rely on the ally for "advice", so that had to go away. In any case, eventually he did want a campaign where he was a solo PC, and the Padawan was born. I gave him boatloads of XP (300+ to start) provided he didn't min-max, free access to three related (Sentinel) trees at once, etc. It's almost surprising how much XP you can spend and still have large areas of relatively poor odds. Anyway, this PC is broadly capable, which takes the pressure off having to find an "expert" for every little thing (though experts are still sought out when, mechanically speaking, a 4+ dice pool is needed to have a chance at something).

I will say it's actually good GM training to run just one PC it, it makes you more flexible and inventive with a larger group. Failure is much more common, so "failing forward" requires a lot more creativity.

31 minutes ago, whafrog said:

Conflict is a lot tougher to scale. Any string of cold dice can put the lone PC    in serious jeopardy, so you always have to have a backup plan (capture & escape, Coruscant free-falls that land on passing speeders (or snagged by a large predatory bird), the arrival of "cavalry", etc).

That is such a good fit for SW with its cliffhangers and shocking twists and general pulp action style.

Silhouette Zero is technically only the GM and Player (the brother, Matt). Other than the main character, they both tend to co-run all the "NPC" supporting cast, many of whom are fully statted as PCs. They roll Force dice for each active character in the session.

I'd probably do it this way. Have a main PC that drives the story and the GM can't touch, then maybe two supporting characters that fill necessary holes in both the narrative and skill pool.

Party of One is a series of one-shots in a plethora of systems with only a GM/Player as well. Lots of potential inspiration there.

Yeah, my response echo's Rogue09. Add some supporting NPC's.

I've always found that with a single player and the GM, you should really go in depth with the role-playing and story development. As far as the supporting cast, that really works well and is often found in video game based RPGs, but if abused by the PC they will move along and leave the PC high and dry, especially when the ship needs a lot of repair work, and the PC being the hero is just a jerk to them, so they find work elsewhere.

I might suggest that the player PC have two initiative slots as they recommend you do for the NPCs who should be tough and represent a real threat to the players when they outnumber the NPCC villian/opponent. Or a sorta reverse adversary option give the PC 1 rank in that talent, so the for combat checks targeting them, the opponents difficulty pool is upgraded once (per rank). Provides a slight advantage in combat, and the initiative option could be used only when the player PC is heavily outnumbered.

I recommend thinking of it almost like a computer RPG. Generate some NPC "party members" that you the GM roleplay in non-action scenes, but whose skill rolls and combat actions are controlled by the player during structured encounters. Your player is Shepard/Revan, these NPCs are the equivalent of Garrus/Bastila. Make their stories interesting but secondary, to fit that theme, and give the player's main character plenty of opportunities to help them out with their problems and help them grow as people in the equivalent of "side quests."

Add in a Droid NPC to have a few Skills the PC is missing, just an off the shelf model the Player can mod throughout the campaign. Have the Player order it around but you play it.

• Give the player companions - Give the player flushed out and fun companions that you role play. Unless he/she prefers you to roll, I'd let the player roll skill checks for these characters. Do be careful not to let the player abuse these characters, especially when it comes to fishing for plot points or solutions to problems the player needs to be solving for themselves, also don't let the characters out shine the player, the player should be the star!
• Give the player time - Give the player time to shop, gear up, take their time picking out a ship to buy and gamble if they want to spend time at the table and so on. In games with multiple players, it can often be difficult to have one player sit and gamble for hours while the rest do nothing, or shop for new weapons and armor, or what have you, but not so in a solo player game. The player has all the agency and there is nothing wrong with letting them really take their time and live in the game world for a session or two even.
• Give the player twist - This is also something you want to do in group games, but it can really be explored in a solo player game. This will require you to get the player to really flush out the character's back story, but it will be worth it when minor details pop up in ways the player never expected or even major plot points appear in ways they didn't see coming. Maybe one of those companions betrays the player and steals his ship? Maybe the droid he just fought was designed by that evil scientist he use to work for? Maybe the man she was hired to kill is her long lost brother, and by the darkside has he turned out to be a real awful monster? In a solo game you can really bring in all sorts of twist and hooks, that can get lost in group games.