I am playing descent 1 and when i try to play these levels the game instantly crashes and says can't open file <missions/insert level name here.RDL>. It does not matter if i play single or multiplayer the result is always the same.

the levels affected are.

Abyss 1.0.
Boli.
Bushwak.
Captain Rye's Rescue.
Caverns Of Croix 1.1.
Century Post Excelsior As...…something….
Chaos At Bay 32.
Cicero Outpost.
Death Star.
Deep Frost.
Deep Pit Mine.
Destination Saturn.
Devil's Heart.
Diplomatic Rescue.
Gehenna.
Ice's Sewers.
In Square Out.
Johnny's Way.
Little Devil By Tac.
Neural Intensity.
Pyramid.
Roundup.
Satellite.
Secrets.
Seti-Alpha V.
Slightly Modified.
Spank You.
Surprise!
Switch.
T.F. Military Depot.
Tartarus.
Technic Cleansing.
The Keep.
The Pit.
Turncoat.
Ufp1771g.
Venus Construction Zone.
Venus Production Plant.
Venus Waste Processing Plant.
Both of Viper's Playground.
Abandoned Base 1.0.
Chambers Of Fun!
Death Arena.
Halley's Comet.
Hunting Halls 1.0.
Jaxx.
Mean Streets By Tac.
Nick The Blue Snake.
Ports o' Kill 1.0.
Redrum.
Seals.
T-zone By Tac.
The Jolly Green Gyro.
The Staircase.
The Temple.
The Temple On 3rd Ave.

None of these have HOG-files and instead the have RDL-files.

No, that wasn't a bug report. Vertigo misses the necessary assets.

It was meant as a warning to other users to prevent anyone to waste as much time as I did trying to debug the issue.

Hello.

I'm sorry for any potential necro of this thread, but...

I have installed the DOSBox version from GOG, through Galaxy, and then placed the files in the Vertigo.zip in the main instal folder of D2, as stated in the OP.

However, I'm met with the error on the pic (it is a crash). The intros load fine, only the actual level crashes it.

Any help?

The game should not crash over missing assets. It should display some message to the user about the missing assets, then fail out gracefully. If it crashes, that is a bug you should report to the program's maintainers. For crashes with the original game, you should contact GOG Customer Service. As an alternative, you could try using one of the free source ports, which may already have an appropriate fix.

As a newbie to Descent I didn't even know there was additional content. Nice. It's always good to have more Descent to play.