On a flight, you might not have much room for a mouse so I would actually suggest sticking with classics, one of which that comes to mind is Duke Nukem 3D which would definitely tide someone over for 2.5+ hours. With a mouse and given that you're going to be offline during this time, a shooter with a decent single player campaign would be preferred I think, so I'd highly recommend Half-Life, Half-Life 2, Portal (not really a shooter per say but an incredible first person puzzle game that involves shooting portals to relocate both yourself and various objects), and Portal 2. These are some of the most lauded first person games that exist.
Beyond that, I'd recommend one of the Tom Clancy's Rainbow Six games (Tactical/realistic shooters with interesting plots - I'd say either the original or the second, Rogue Spear, but not sure how well these work on Windows 10. Also, I'm not sure about the newer sequels because I haven't played them). The Call of Duty series, generally, has interesting campaigns. If you happen to enjoy Star Wars, I would recommend Jedi Knight II: Outcast which starts off completely as a shooter but then you get a lightsaber and force powers which mostly replace gun usage, although you can still use anything in your arsenal. If you enjoy a bit of horror, Doom 3 might be up your alley. For a realistic survival horror game, I would recommend the S.T.A.L.K.E.R. series.
I should note that most of these suggestions are older games because they tend to have more of a single player focus unlike most of today's shooters and it's almost guaranteed that they will run well as long as they have no problems with Windows 10.
Edit: Thought about it a bit more. If you don't mind some RPG in your shooter, Deus Ex: Human Revolution is a more modern game that would probably run decently on the SP4. It has a lot of options in how to approach encounters (including stealthy and non-violent resolutions along with going in "loud") and has a fairly interesting story. Another good one is No One Lives Forever, one of the best spy games to exist that's part parody but also a great shooter with some stealth elements. The Serious Sam series might also be worth looking into as well which is more of a straight up shooter where you blow up many many aliens.
