A downloadable game for Windows, macOS, and Linux

Explore castles and caves in your quest to defeat the guardians of the under world and make your escape. A fast paced, action packed, retro styled 2D platformer. Straight out of the 80s in glorious 32 colours.

Play the practice map to learn how to play, then take on four more exciting maps.

Keyboard Controls

Cursor left/right - Walk left and right

Cursor up - Jump and move up rope

Cursor down - Duck and move down rope

Z - Fire

X - Pickup/drop and drop off rope

Esc - Quit

PlatformsWindows, macOS, Linux
Rated 4.9 out of 5 stars
(18 total ratings)
AuthorBitGlint Games
GenrePlatformer, Action
Tags2D, Action-Adventure, Indie, Pixel Art, Retro, ZX Spectrum


Undrium_Portable_Win_x64_1.1.zip 36 MB
Undrium_Portable_Linux_x64_1.1.zip 63 MB
Undrium_Portable_Linux_Arm64_1.1.zip 60 MB
Undrium_Portable_Mac_x64_1.1.zip 63 MB
Undrium_Portable_Mac_Arm64_1.1.zip 62 MB
Undrium_Portable_Win_x86_1.1.zip 95 MB

Install instructions

Windows - Download, unzip and run "UndriumDX.exe". You may be asked to install .Net Core runtimes.

Linux - Download, unzip and run "UndriumGL"

Mac - Download and double click the application package. Adjust security setting to allow the game to run.


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Hi, I'd like to volunteer to translate your game from English into Brazilian Portuguese.

Thanks for the offer, that's very kind of you. The game doesn't currently support language selection but it's something I'll add if I go back to it at any point.

No problem :)

Fantastic thank you so much! ;-)

Thanks! :o)

Looks like a very fun game. We recommended it at position 02:22:35 in our last live stream and showed the video trailer for it. Subscription to our YouTube or Twitch channel is welcome. 🙂

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Thanks for the mention.


Fantastic game. Well done!


Thx for the follow mate! :)

Welcome! :)

very good


Lovely game sir, here is my tribute to you.   I remember talking directly to you in the past about Class of 99 - you were even awesome enough to put me in the credits all those years ago.

Anyways, heres my journey of this great game you have made...

Thanks, I'll watch that later, just gotta go sand down a door frame first! Thanks also the Melkhior's Mansion review last year. :o)

I could sum up my Undrium experience in three words: playability, nostalgia and good taste. First Melkhior's Mansion and now a new masterpiece. Richard, you are a genius!

Thank you so much, my friend.

You're welcome. Thanks for those kind words. :o)

Not working for me, error - windows cannot access the specified device, path or file, not appropriate permission to access the item.

Sorry to hear that. Drop me an email and I'll see what I can do. My email address is here...  BitGlint Game

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What a fantastic game! Had a quick go today, but hope to dig into it properly later. I love the visual style!

One small note; the tutorial didn't cover which buttons to press. It's a very small thing, but since the game is so intuitive otherwise it would be great if it mentioned which buttons do what. (I know I can read it on this page, but still.. :) )

Thanks for the feedback, glad to hear you're enjoying it. That's a fair point regarding the tutorial. When you're developing a game, and playing it day in, day out, it's so easy to forget that someone completely new to it is not going to know these things. If I do another release, I'll extend that map to cover it. :o)

I totally love this game - the look and feel are great. Thank you. I think I need to make a retro 8-bit Mega65 tribute to it! 

Glad to hear it, thanks for the feedback.

podria sacar una version win 32x,gracias

Sí, he subido un archivo zip Win32.

It looks like a fantastic game but it doesn't work for me. I downloaded the windows version, I have windows 64 bits, but when I double click on the executable UndriumDX.exe nothing happens, nothing opens. I even tried to open it as administrator and still nothing happens :(

Hmmm, that's odd. Have a look in the Undrium folder and you should see a sub folder called Log. Can you email me the files in that folder? My email address is here...  BitGlint Games

when I try to start the game there is no prompt to install runtime, but I have installed it before and now the game works perfectly. Congratulations on the game, it's great!

Ahh brilliant, enjoy the game. :o)

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Does your Windows have installed the Windows Desktop Runtime thing? I had to install it cause I got a message about it. The file is "windowsdesktop-runtime-6.0.16-win-x64.exe". After installing it, works ok. Try that!

when I try to start the game there is no prompt to install runtime, but I have installed it before and now the game works perfectly. Congratulations on the game, it's great!

Good morning, excellent game! How likely is an Undrium_Portable_Linux_Arm64_1.1.zip ?


Very likely. I'll sort one out later today, just doing a spot of decorating at the moment. :o)


The Linux Arm 64 version is now available. I have no means of testing it, so please let me know how you get on with it.

It works. Thanks. There are some bugs in the menu, on Windows x64 and Linux ARM x64. Sometimes you open ABOUT and the game asks for yes and no and suddenly quits. Try it out yourself! Nothing to worry about though. Nevertheless excellent work. I am quite sure you made many many people very happy now.

Ahh brilliant, glad to hear it works. Not sure what you mean by that thing on the "About" screen. Would you be able to email me a screenshot to the email address here... BitGlint Games

Bestial. Congratulations.




very good


Can't get it to run on Mac.  Every time I launch it It almost instantly quits with the "UndriumGL quit unexpectedly" error.  Doesn't even open a game window.
Running macOS 13.3.1(a) on a 2019 15" MBP. 

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I've had a couple of Mac users report it doing the same. The crash reports have shown that it's trying to run from "/private/var/folders/". Where are you trying to run it from? On my Mac, I just double click the app bundle icon from the Downloads folder. I'm a bit of a novice when it comes to MacOS, so be gentle! :o)

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Copied it to the Applications folder.  Will try from somewhere else and let you know.

[edit] Tried running it from the downloads folder and it does try to open a game window (the title appears on the taskbar at the top of the screen) but then it just crashes out again with the same error.


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Also having an issue with the Apple ARM64 build: https://gist.github.com/gingerbeardman/0afcd9c849b41048d3e58e0ce659823c

The Apple x64 opens just fine though.

Thanks for info, useful stuff.

Underwurlde toughness is back!

Little bit easier this one.

Ultimate, cheers

You're welcome

Hi. Thanks for the game. 

On Windows (64) I have this error with the latest .net runtime:

Value 0.01 is not a floating point value

System.Exception: Value 0.01 is not a floating point value

   at Undrium.Components.XmlHelper.GetFloat(String itemName) in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Components\XmlHelper.cs:line 178

   at Undrium.Objects.AmbientSoundDefinition..ctor(XmlNode xmlDataNode) in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Objects\AmbientSoundDefinition.cs:line 107

   at Undrium.Components.SoundHelper.Initialise(ContentManager content) in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Components\SoundHelper.cs:line 168

   at Undrium.Main.Initialize() in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Main.cs:line 155

   at Microsoft.Xna.Framework.Game.DoInitialize()

   at Microsoft.Xna.Framework.Game.Run(GameRunBehavior runBehavior)

   at Undrium.Program.Main() in C:\Dropbox\MyGames\Monogame38\Undrium\UndriumDX\Program.cs:line 22


Hi, thanks for the info. What regional settings are you running under?

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Windows 11 / French (France)

Ahh, I see the problem. I've just uploaded version 1.1. Would you mind trying it?

It works :) Thank you ! A perfect Underwurld remake :)

Ahhh brilliant, thanks for letting me know.

Absolutely fantastic quality, looks and plays beautifully.


Thank you very much for making this free. It looks awesome.

On Linux, I get this error when trying to start:

Value 0.01 is not a floating point value
System.Exception: Value 0.01 is not a floating point value
   at Undrium.Components.XmlHelper.GetFloat(String itemName) in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Components\XmlHelper.cs:line 178
   at Undrium.Objects.AmbientSoundDefinition..ctor(XmlNode xmlDataNode) in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Objects\AmbientSoundDefinition.cs:line 103
   at Undrium.Components.SoundHelper.Initialise(ContentManager content) in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Components\SoundHelper.cs:line 168
   at Undrium.Main.Initialize() in C:\Dropbox\MyGames\Monogame38\Undrium\Undrium\Main.cs:line 154
   at Microsoft.Xna.Framework.Game.DoInitialize()
   at Microsoft.Xna.Framework.Game.Run(GameRunBehavior runBehavior)
   at Undrium.Program.Main() in C:\Dropbox\MyGames\Monogame38\Undrium\UndriumGL\Program.cs:line 22

Hi, thanks for the info. What distro are you using and what regional settings are you running under?

Hi, I've the same error.

Linux Mint 21.1 ("same" as ubuntu 22.04), lang : Fr (french)

It was a regional issue, my bad. Can you try version 1.1?  I've just uploaded it.

yes, it works !

Thank ! :)

Brilliant, thanks for letting me know. Have fun.

This is stunning - thank you. Are there any joystick options on Mac or Win please?

Thanks. Yeh standard gamepads should work on Windows. I don't have the kit to test on gamepads on Mac.

very good


Awesome, another quality masterpiece. Wonderful to finally see this one remade as well

Thanks :o)

I really want to check this out,I really enjoyed Melkhiors,Do you have an ETA?

Yeh it shouldn't be too long now, hopefully just a month or so.


Looks great,Can't wait to give it a go!

Thanks, hoping to have it done by the end of the year.

looks glorious


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This is excellent! It runs great here on Windows 10 (latest version). Any news on the progress of this project?

Thanks. It was originally written as a proof of concept for a scrolling Underwurlde with authentic gameplay feel. It's currently top of my list of projects to work on next.

Thanks for that quick reply! Well, I for one would love to see this completed. Those Ultimate games were just so amazing back in the day. This brings back many fond memories. I love the direction you have taken it in. All the best.

Cheers. Watch this space! :o)

Completely freezes comp (Win 10) upon loading, no screen loads or anything, just frozen desktop needing manual restart of PC.

Tried twice, same thing both times.

Hi, that's very unusual, sounds like it could be driver related. Is your PC up to date with all Windows updates and graphics drivers? Do you have any unusual hardware installed?

Plays fantastic, thank you

Thanks, glad you like it ;o)

Yes this is great, smooth and slick, and the pixel work is authentic and polished. Its a great POC. I love the added keys and doors element as well.

Thanks, appreciate your comments, especially about the pixel work because I'm not very good at that, hence the simple flat look.

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Brilliant! Fun and frustration in equal measure, just like the original.  Really enjoyed how it initially replicated the original map before branching off into it's own. Lots of nice little touches, like the "2021" chest of drawers and the Atic Atac-styled keys and doors. I managed to escape via the upper exit on my second go, but that felt more like blind luck than canny gameplay.

Keep up the good work. You owe to it the 'wurlde to complete this one.


It wouldn't be Underwurlde without that "frustration factor" :o)

Lovely.  Such memories :) Plays really well. Thankyou.

Thanks,  glad you like it.

Great old school graphics

Thanks. I don't normally pixel, so it's been a struggle!! :o)