Getting 100% was... just like playing Portal 2 all over again. I'm serious, same level of quality.

approximate amount of time to 100%: 5-10 Hours
Estimated achievement difficulty: 3/10
Minimum number of playthroughs needed: 1
Multiplayer achievements: No.
Missable achievements: No.
Point of no return: No.
Grinding Achievements: No.
DLC-Only achievements: No.
Time-gated achievements: No.
Speed-run achievements: No.
RNG-achievements: No.
Does difficulty affect achievements: No difficulty choice.
First achievement unlock: Most likely "sending a message" in Chapter 2. "Just in time" is available in chapter 1 but most people won't get it.

Note:
Chapter and room select available.

I rarely see a mod with this amount of quality and work put into it. If I didn't know better i'd say this was an official launch from valve, I can't understate how professional this looks. The voice acting is really good as well, and the puzzles (including the new mechanics) are challenging enough for portal veterans.

And on top of that it's free. Just play it!

Getting 100% was... just like playing Portal 2 all over again. I'm serious, same level of quality. approximate amount of time to 100%: 5-10 Hours Estimated achievement difficulty: 3/10 Minimum number of playthroughs needed: 1 Multiplayer achievements: No. Missable achievements: No. Point of no return: No. Grinding Achievements: No. DLC-Only achievements: No. Time-gated achievements: No. Speed-run achievements: No. RNG-achievements: No. Does difficulty affect achievements: No difficulty choice. First achievement unlock: Most likely "sending a message" in Chapter 2. "Just in time" is available in chapter 1 but most people won't get it. Note: Chapter and room select available. I rarely see a mod with this amount of quality and work put into it. If I didn't know better i'd say this was an official launch from valve, I can't understate how professional this looks. The voice acting is really good as well, and the puzzles (including the new mechanics) are challenging enough for portal veterans. And on top of that it's free. Just play it!