Trouble with 2002 ADO's E1M9

I have started playing 2002 A Doom Odyssey: 10th Anniversary Edition and I am having a hard time getting the secret invulnerability sphere. There is a "5" sign on the floor pointing to a secret door, but I cannot get the latter to open.

Does anyone know how to do so? Thanks in advance!

I haven't played the map, but after a 10 seconds google search I found this video showing a guy who knows, looks like it opens at 5 minutes after you start the map.

That is what I saw, but it still will not open for me. On my first try, I had been playing the map for over ten minutes when I discovered the secret area with the invulnerability sphere, but the door would still be closed.

JohnnyTheWolf said:

That is what I saw, but it still will not open for me. On my first try, I had been playing the map for over ten minutes when I discovered the secret area with the invulnerability sphere, but the door would still be closed.

It opens exactly after 5 minutes, It's 'Door Open Close (opens after 5 min) action, so you must get there at exactly 5 minutes.

The above reply might not make it obvious, so I'll add: The door opens 5 minutes after the map was started, stays open for only 5 seconds, then closes again, and never opens again anymore.

... What was the mapper thinking?

Anyway, got it. Thanks a lot!

Yep, you have to wait for 5 minutes hence the number 5 and arrow on the floor. The door opens for 6 seconds and closes again. (Sector effect 14 Door raise after 5 minutes) In the original 2002ado, this secret was totally unmarked.

JohnnyTheWolf said:

... What was the mapper thinking?

I was certainly thinking of very hard to find top secrets all those years ago.

Eh. It strikes me as more frustrating than hard to find, as it could be easily mistaken for a bug, like those unobtainable secrets in vanilla mapsets.

But make no mistake: apart from this one secret, I very much enjoy the WAD so far!