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Welcome to the RigelEngine wiki!

Modding capabilities

Like the original DOS executable, Rigel Engine supports replacing individual files from the game's data pack file (NUKEM2.CMP). For example, when a file called L1.MNI is found next to the .CMP file, it will be used instead of the version found inside the .CMP. This makes it possible to use existing patches and mods, like the sunglasses patch.

On top of this, Rigel Engine features enhanced modding support. At the moment, sprites can be replaced with PNG images, which makes it possible to swap in high fidelity versions of enemies and other game objects. The game looks for a folder called asset_replacements next to the .CMP file. If it exists, it looks for files called actorX_frameY.png, with X and Y being the actor ID and animation frame index, respectively. For each image file that's found, the game will load that file instead of the version in the original game data.

Further support in this direction is work in progress. Planned so far:

• Replaceable tile sets and backgrounds
• Replaceable music
• Replaceable sound effects

Info for developers

• Architecture overview
• Rendering backend
• Guide: Reverse engineering enemy behavior
• Implementing new enemies/actors
• DukeScript

Debugging features

At any time, you can press F6 to toggle showing a FPS counter.

While in game, you can:

• press D to toggle showing some debug info text
• press B to toggle showing objects' bounding boxes. objects that harm the player on contact will have their box drawn in red, others in green.
• press C to toggle showing collision data. This draws yellow lines on top of the map in all the places where tiles are considered solid. It also colors in ladders and climbable pipes.
• press G to toggle drawing a tile grid on top of the map
• press S to enter single-step mode. This will stop time from advancing in the game, making everything stop. Pressing space bar advances time by exactly one frame. Pressing S again goes back to normal.

Differences to the original Duke Nukem II executable

Optional modern enhancements

• Widescreen mode: Uses the full width of the screen to draw the world during gameplay, instead of black bars on the left/right. This alters gameplay, since some enemies can come into view sooner than intended, and hidden parts of the level can become visible.

Improvements

• Sound and music volume can be adjusted
• No loading screen when starting a new game/loading a saved game
• Menus are much more responsive
• Multiple sound effects can play at the same time
• Lifted limitations for number of simultaneous explosions/particles/effects on screen

Fixed bugs

This is a list of bugs that occur in the original Duke Nukem II, but are fixed in Rigel Engine.

• When music playback is disabled, the Apogee Logo movie will keep playing forever until a key is pressed, instead of moving on to the intro movie
• Placing a Blue Guard enemy in the air will cause the game to lock up due to infinite recursion
• The missile is missing one frame of animation in its "launch" sequence when shot from the left side
• The horizontal sliding door actor has incorrect collision initially: The rightmost tile is not solid, and shots can pass through. Once the door has opened and closed once, it behaves correctly.