Right. I see. If you find a fusion as loot, can you whack that on a weapon for free using 10 minutes and an arcana skill or does that still use a cost?
If you find an unused fusion you can have a character trained in engineering or mysticism affix it to an eligible weapon for the cost given in the table. There's no cost savings compared to making the fusion yourself but it does mean you don't have to have as many ranks in mysticism as the fusion's level like you would if you were making it yourself. Given how equipment levels work in Starfinder I wouldn't expect that to be much help.
Character creation (and advancement) and actions are really important things to understand and differ significantly between Starfinder and D&D 5e. You'll have a lot of trouble playing if you don't know how to create a character or use actions. After that it's details. It's worth going over how attacks of opportunity work since it's much easier to provoke in Starfinder than in D&D 5e. Like in 5e managing threatened squares can be a major part of a martial character's job.
When I switched my game from 5e to Starfinder I included these tutorial videos from the Basics4Gamers channel in the reorientation packet:
Actions work differently in Starfinder than in 5e. Make sure to read pages 244-249. This video covers essentially the same information https://www.youtube.com/watch?v=d7VapCH2-z0
It is much easier to provoke opportunity attacks in Starfinder. See page 248-249 for details. This video is also helpful https://www.youtube.com/watch?v=H-mvDv0Rrik
In Starfinder’s high tech setting most intelligent enemies have ranged weapons and accordingly cover is of greater importance in this game. See page 253-254 for details. Ignore the diagram at the bottom of page 253. It conflicts with the rules text. You might also wish to view this video, which describes clearly how it all works with good examples. https://www.youtube.com/watch?v=NlCzJGDvkT0
Make sure the players know the objective is to win the race. It's fairly common to get the mistaken impression you only have to beat Ratrod. Related, one of my players got super fixated on sabotaging Ratrod's racer even after I told him how hard it would be to gain access without any of the pit crew catching him and he'd get tossed out of the competition if he got caught even once. He got caught so I had him maintain the distance tracker during the race. Basically I had note cards with the names of all the racers and little miniature ships on them and had him add up and record the distance each had travelled each round, repositioning the cards as necessary to keep them in order by placement. I intended to have a scaled down strip map of the track with distance markers to advance the racers along but I didn't get around to it.
The NPC racer with the supercharged engine blew up right out the gate. For PCs, I'm pretty sure using the supercharger right away is the worst possible strategy. Blowing up early virtually guarantees a loss while activating it later will reduce the amount of distance you might have to cover at half speed. NPC racers also tend to target the front runner so the lead you gambled for will erode even if you don't blow up. The most important thing is to consistently pass your piloting checks while having a decent base speed.
You can slightly increase the number of people rolling dice during the race by letting a copilot use Aid Another on the piloting checks.
I got a bit of sticker shock from how much grenades cost and I've seen someone else mention it too. Prices tend to line up so that the cost of a handful of grenades will buy a weapon of the same tier, and that would tend to discourage people from buying them. Is that an actual problem, and if so what cost would make people use them more?
My thought on how to do more realistic shotguns was to borrow the bit about ignoring concealment from the existing blast rules while otherwise rolling attacks against single targets the same way you do with rifles, then balance that advantage by giving a poor range increment and perhaps slightly lower damage than rifles of the same level. I'd consider going into special rules to represent terminal ballistics of shotgun pellets versus bullets to be excessive complexity.
1) The rules for levelling up say that if you increase your intelligence score and get additional skill points per level, you apply the increase retroactively.
I remembered it working this way in Pathfinder but I wasn't able to find the corresponding rule in Starfinder at first. Thanks for pointing this out, I looked harder and found it on page 26, second paragraph of "Step 1"
It's basically a blue star plasma cannon, surely? It has the Explosion and Unwieldy properties and takes the same sort of battery as any high-tier energy weapon with usage so high it only gets ten shots. Single-target damage isn't as high as you might want but then no area effect energy weapon has any business beating a level-equivalent reaction cannon in that regard.