fap.
Up.and Strike force hereos also Last stand Last stand 2
pretty sure these don't need internet but not quite surealso if you plan on playing any of these make sure you first-time launch it beforehand.. i did that once on an 8 hour drive and didn't have stuff to do for the whole timeassuming you like puzzle games cause you played portal 2.. i suggest you play:(launch steam AHEAD OF TIME. then you'll be able to play offline)SpaceChemAnd Yet It MovesTrineCave StoryBraid..based on Minecraft:Terraria (old but still pretty fun.. don't think you need internet?)..and i've never played SR3 so I wouldn't know.