A casual speedrun on Black Mesa area from Anomalous Materials to Xen by using Infinite Health Door 2 on Surface Tension.
The speedrun was necessary to be finished after Lambda Core to a bug that exists in Gonarch's Lair where the level text doesnt appear as expected - this means: the game doesnt recognize it as being a new level - and crashes the game on first loading moment.
When black screen comes after IHD 2 success, due to Tripmine explosion, its expected the game to produce a failure/softlock message (since guard is killed) where this doesnt happen - as you are free to proceed to next area. As a result, this provoke a source code conflict where a failure/softlock is interpreted as success at same time - since you are free to go. *This thing does NOT happen on PC version of the game: Game behaves normally with IHD 2 usage.* This programming error seems to be exclusive to PS2 port.
The black screen is gone on next loading area, but you need to go back and forth to that area again once to avoid game crashing in "Forget about Freeman" level. However, the crash in Gonarch's Lair in unavoidable.
Thus, the only way to speedrun the entire game is by using the Infinite Health Door 1 on Surface Tension which is a thing that many speedruns already knows and already does it. IHD 1 is harder to reproduce than IHD 2.