Closing in on Being Ready to Run Starfinder

 When I first started running D&D, I had a couple advantages. One was that one of my players was already familiar with 5th Edition, and could catch some of my newbie errors (like when I thought that every player got XP for the full encounter, rather than dividing it between them). Another was Acquisitions Incorporated, which had been showing off 5th Edition since it was called "D&D Next."

I'm not entirely without advantage here, though. While I jumped into D&D as a DM after only some brief experience playing the Song of Ice and Fire TTRPG, at this point I've been running and playing D&D for several years. Starfinder's systems are different, but not so different that it's unrecognizable.

What I think is perhaps trickier is recalibrating my sense of scale. In D&D, things like ability checks don't get that much harder as you level up. Given that you're unlikely to increase ability scores that aren't your primary focus (like a Rogue's Dexterity or a Wizard's Intelligence) at least until far later in the game, a DC 20, say, Intimidation check for a character who isn't proficient in it and isn't Charisma-based is probably going to be just as hard at level 1 as it is at level 20.

However, in Starfinder, bonuses go up a lot more as you level. Every level, you gain additional skill ranks, so even if your Intelligence isn't going up, your Computers skill (which is used to hack or otherwise use computers) might go up each level if that's something you want to focus on, which you might want to if you're the party's science officer on their starship.

Each class has a "base attack bonus" that they add in addition to Dexterity or Strength to their weapon attacks. This typically starts at 1 but goes up to 15 for most classes by level 20, or to 20 if you're a Soldier (in fact, for soldier's the "BAB" is just equal to your level.) In D&D, by level 10 you probably have a modifier for your primary ability at +5, and your proficiency bonus at that point is +4, meaning you'd have an attack modifier of +9. Then, if you're a martial class, by that level you likely have a +1 or +2 weapon, so you could have a +10 or +11 total bonus to hit.

In Starfinder, I believe you could get a +5 to your Strength or Dex by that point, and if you're a Soldier, you'd have a +10 BAB, meaning you've already got a +15 to hit. Now, as far as I can tell (and again, I'm a total noob here) there's less of a chance to get a +X modifier on a weapon's chance to hit. (There is a "Weapon Focus" feat you can take that adds a bit to it, but it doesn't seem to come with the weapon itself.)

Thus, while nothing in D&D (apart from player characters, potentially, as well as rare monsters with high AC and the ability to cast the Shield spell) has an AC higher than 25, Starfinder can afford monsters with significantly higher ACs given that 25 would be a 50% chance for a Soldier at level 10. (For example, one of the highest CR creatures in the Alien Archive, the Endbringer Devil, has an EAC of 35 and a KAC of 34).

Likewise, weapon damage scales up a lot higher as you purchase more advanced weapons, so while in D&D, class features like Improved Divine Smite or the increased damage of Rage will gradually increase your damage output, Starfinder sees your damage going up by huge amounts - a level 1 weapon might do 1d6 damage, while an equivalent level 10 one (which you could likely get around level 10) could do 3d6.

To sum up the past several paragraphs: I'd need to seriously adjust my sense of what is a big number or a small number for this new game's systems.

Initially, I was pretty intimidated by the class sections, given the vast array of abilities. However, Starfinder (and I think Pathfinder) is built around letting you make a lot of choices in building your character, which means that for all those features, you're only going to be choosing one at a time. For a one-shot involving first-level characters, that means that once the character sheets themselves are put together, it's not actually going to be all that complicated.

My next move, then, I think, is going to be to figure out some fun encounters that won't be too complicated, but will also show off the sci-fi elements of the game in contrast with D&D. Even though Space Goblins seem like an obvious first foe to face, I might try to do something a little weirder.

I'd also love to have a starship combat in there, though I think that might be better to save for a second session - let people get to know their own characters before we introduce the complexities of space battles.