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Doomsday Machine - A Chaos Engine TC for GZDoom

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Another ridiculous idea of mine: Doomsday Machine!

Doomsday Machine aims to bring the gameplay of the Amiga classic The Chaos Engine to Doom. I have tried hard to convert everything from the game faithfully into the 3rd dimension, including almost complete replicas of the levels.

One of the things that inspired me was this twitter post by Antto Koponen, described in greater detail on his DeviantArt page:

Gameplay overview:
The first two levels have been included.

Choose between three different characters:

  • The brigand is an allrounder with average speed and health. He is armed with a rifle. His special power is the shotburst, which shoots powerful bullets all around him. 
  • The Preacher is fast but fragile. He is armed with a lightning gun that is weak but it's rays travel through enemies. His special power is a first aid kit he can use to heal 50 health points.
  • The Navvie is strong and slow. He is armed with the powerful bazooka. His special power is the dynamite. Throw it into a group of enemies to kill them all.

While exploring a level, keep an eye out for ambushes. Cave entrances and holes in the ground will appear that spawn monsters. Kill monsters to collect the coins they drop (no use for cash yet, though). Special powers work as follows: If you have unlocked one (such as the special powers you get from the start as part of your chosen character), you will first use all you have collected of the same kind before using the universal special power items (orange bars in your status bar). If you haven't unlocked a special power, you will simply run out of that item when it is depleted. So, special powers are exlusively used for your unlocked powers.
To open the exit door, you have to activate a certain number of nodes by shooting them until their outer shell breaks.
Silver and gold keys open or close different paths through a level. Sometimes, collecting items or just reaching a certain spot will do the same.


On developing this TC:
It started out as a newfound fascination with this classic game featuring the incredible artstyle of Dan Malone. In lieu of a proper new game set in that universe, I tried to adapt GZDoom as a way of finding out wether a top-down action game would be a good fit for the first person perspective. I had to learn how to zScript status bars and use GZDoomBuilder to make my first real maps, with heavy use of ACS scripting for the game logic. 
The weapons were all carefully modelled after their original sprites. Some graphics also had to be converted or even created from scratch. 
In hindsight, converting the levels one to one doesn't work too well since TCE obviously has no concept of shooting up or down, and the already confusing labyrinthine levels of the original game become even more confusing in first person view. 
The gameplay limitations might also be confusing for the player, such as being blocked by water/mud and not being able to jump down from cliffs. 
The levels were created with a tile-based approach, which means having seperate small sectors for each ground feature. This affects performance in the second level because there are also no "hard" blocking walls thoughout the rather large area. For new maps, I would probably do it like the surrounding "off-limits" areas of the second level, where I assembled a texture from tiles beforehand and just slapped it onto one big sector. This would also make sound zone boundaries far more easy to set up. 
In some places, nodes can simply be shot from afar or above when they would be unreachable in the original game due to some  bridge or stairs appearing or disappearing. I have thought about using special nodes that can only be activated from a short distance. 
On the weapons: I like the bazooka, the lightning gun doesn't look as good mostly because I didn't bother with creating a proper texture for it. The rifle is even worse because I couldn't find a hand graphic for it. 
Some Bridges on the second level are models, some are normal map sectors, so not all will show up on the map. 
I'm not sure if I will ever sit down and create more levels, mostly because of the heavy work involved in scripting all the ambushes and puzzle elements.





Initial version. Two levels, three characters, three special powers.











The Bitmap Brothers
Graphics            Dan Malone
music            Richard Joseph / nx666 (mp3 files)
Beetle            Bullfrog (Dungeon Keeper)
Rockman            Raven Software (Mummy/Golem)
Hitflash effect        Blue Shadow

Edited by Cherno

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Wow, very interesting. I love TCs that are not totally obvious (as in "Blood" for Doom, etc.) and go a more creative way (HocusDoom, Chaos Engine...). The pixel art from Dan Malone was always one of my favourites ever and to see it in the Doom engine is really interesting. I have to give this a go asap and hope work on this continues. I am not sure about the weapon, though. Looks a tad out of place. Could use some Dan Malone style dithering. :p

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Well, the HUD weapons are problematic indeed because they coudl never mesh well with the low-resolution, yet detailed pixel art in the level. A weapon sprite at 2x or even higher resolution would look horrible so I'm not sure what could be improved other than the usual cleaning up of model rendered sprites.

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Very much so! I saw this over at the EAB as well.


While I find that it isn't very much fun to play due to the reaons mentioned by Cherno already, it does look better than I ever thought it might in 3D.

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Here is some gameplay footage:



The Guru Meditation on Youtube has uploaded a very detailed instructional video should you have any trouble getting the game to run.:


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Here are some renders, along with their original pixel art counterparts, of the weapons featured in the mod so far:


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I loved the Chaos Engine! There's not enough decent twin stick shooters these days, but I'll be happy with a FPS conversion.

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