Critical path
Also said as Golden path, Main path
The shortest route through a level or game that still gets you to the end, touching only what is required. The golden path is its richer cousin: the route designers hope most players take, past the things worth seeing.
It tells you what every player is guaranteed to see, which is where the things they must understand have to go. Anything off it might never be seen by half your players.
Say it
“Put the wall-jump tutorial on the critical path, in room three, because every player passes it. The hidden armoury can stay off it.”
Where you’ve seen it
The warp zones in Super Mario Bros. shrink its critical path to eight levels of the thirty-two: 1-1, 1-2, 4-1, 4-2 and all of world 8. Everything else is optional, which is why speedruns take that route.
Not to be confused with golden path
Studios use the two loosely. Where they differ, the critical path is the least you can do, and the golden path is the route the designer intends. Speedrunners take the first; a first-time player should find the second.