Any good games that are 1-2GB?

Half life is pretty small actually, mine is around 2 gb but it have cs and 3 mods. i think that in the reality half life weight 500 mb so i suggest you to download some mods like paranoia and afraid of monsters after finishing the main campaign and have like infinite fun, the desura have like 150 mods for half life and around 600 on Mod DB.
I just finish the Sacred Citadel and it is like a mix between golden axe with castle crashers into a a game whith is fun to play and is beautiful and it is 1.2 gb so it is around 5 hours to play the campaign and i think it is pretty worthy.

Super hexagon, its like 60 meegabytes. Blood of the werewolf too

If you like platformers then Fly'n is a great choice (about 1,5 Gb) and Mutant Blobs Attack is fun aswell (about 300 Mb).
If you like "old school rpgs" then maybe Underrail (about 2 Gb).

Risk of Rain (130 mb), Eldritch (140 mb) The Binding of Isaac (less than 100mb), Paranautical Activity (300 mb), DarkOut (2 GB), Starbound (3 GB), Terraria (50 mb) Lone Survivor The Director's Cut (400 mb on PS Vita)

torchlight 2

dont starve

Project Zomboid.