Half-Life (PC, 1998)

-Linear structure without backtracking to previous levels to progress (optional sidetracking in most levels, partially non-linear level 14 if you want it to be)
-Can skip some parts by creating platforms using the placeable laser trip mines (kinda tricky though), as well as some parts by making NPCs open doors for you (this is tricky and glitchy however as they're not supposed to be doing it, can also skip some parts with grenade or tau ricochet jumps)
​-The Black Mesa complex in the game is mostly an interconnected world rather than separate levels and it's possible to backtrack through parts of the game - there are several points of no return however (beginning of level 5 for example) and generally it's not useful to go back as it would just be for health/armor/ammo or perhaps a missed weapon (and you get multiple chances to find every weapon)
-Gain a long jump ability before the last few levels
-Some escort segments (can tell most NPCs to wait or follow you)
​-Save anywhere (multiple slots, shows current area and time taken)
​-No maps
-Good sense of vulnerability early on (start without a weapon+the scripted events) and at a few other points such as when reaching the surface (continuously spawning enemies+chopper attack) or at the beginning of level 7. Also after the kidnapping in level 9 (lose all weapons)
​-Some environmental storytelling (foreshadowing, large scale environmental changes, G-Man appearances)
-Some decent puzzles (raise/lower water levels to progress, turning off the electricity in one room affects it in adjacent rooms, boxes as platforms - Unreal?, minor stealth element (avoiding the tentacle monster by walking and/or crouching and using grenades), triple conveyor belt+crushers part, platforming puzzle near lasers in level 12, final boss fight) and some good puzzles (push box to get to a spot where you can disable a turret, electricity trap used to take out the big alien in level 7, laser beam in level 11)
-Some alternate solutions to problems (can let a guard in the beginning die to grab his gun, saving another guard lets you access some locked in items, can let a turret deal with some enemies and/or turn it off, use traps or direct combat against some enemies, usable steam trap in level 14, etc)