Nearly all games apart from online RPGs / Strategy games can be played in 30-60min sessions, unless you mean games with a clear end point within that timeframe (i.e. not just save and quit). Nowadays even if a game doesn't have a save feature they usually have fairly frequent checkpoints. If it's the latter I would suggest:
-Oldschool FPS that are broken up into discrete levels that can be treated as almost standalone, generally you'll find these games have levels each lasting around that time, unless you rush through them. Although with the more atmospheric and/or story driven ones, you may find yourself wanting to push on past the hour mark
-Sports games, invariably these will have time limits and you'll quickly get a feel for how many matches you can fit into your preferred timeslot
-Fighting games, either 1v1 matchups like StreetFighter or broken into levels like Streets of Rage
Bad choices would be RPGs, which are inherently analog with few obvious break points, or strategy games, which often have wide variation in the length of each level/battle (taking RTS as an example, you might have some rounds over in 15mins, some lasting hours)