Parallaxian WIP March 2026

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By Kodiak


As Parallaxian nears completion and playtesters are now starting to send feedback, I thought I should share a video (below) of the latest WIP build of the technical testbed, this time showcasing planet Alpinia for a change of scenery from all that desert landscaping of previous previews.

The game's ground attack weapon, the A-TAC, is now functional and can lay down heavy fire on enemy ground positions, installations, vehicles, etc.

The handling of the game has been rewritten for the umpteenth time to simulate analogue inputs using the digital joysticks that the C64 is used to, so that duration of stick inputs matters too, and not just simply decoding directions the stick is pushed in.

That arrangement is coupled with feedback loops to simulate appropriate flight responses, with the plane essentially having seamless transitions between three integrated flight regimes, as follows:

  1. Low speed handling, for VTOL, approaches, etc.
  2. High speed handling.
  3. Dogfighting.


Some technical notes (for those who care about such things):

  1. The landscape is composed of MCM, ECBM (scroll layers 2 + 3 ) and hi-res gfx for this planet, and the panel zone is 100% ECBM with some plexed sprites.
  2. For this planet, the mountains are derived from an 8-bit digitalisation of a photograph of a real world mountain range.
  3. The game now uses only 4 raster IRQs, with most of the interrupt work being performed by the NMI. There are two main reasons for this, i.e., the game has only a small number of long interrupt-only tasks and these are generally assigned to the IRQ, and the NMI allows near cycle-exact granularity, whereas IRQs are on a line-only basis (unless you waste NOPs by shunting their trigger points along a scanline).
  4. The HK's bullets and jet flames are the same sprite; likewise, the Figment's burners and laser / A-TAC are just one sprite, but everything is moved so fast it looks like multiple sprites are in use. This is a more refined version of my much-maligned "toggleplex" concept.
  5. Until I start switching over to developing the game with GMOD4 in mind, the I/O space under $D000-$DFFF is now used for code, including subroutines called by the main loop. This is achievable by ensuring that the state of $01 is stored by each interrupt service routine (ISR) when one is triggered and then it is restored at the exit of each ISR.


(NOTE: The video misses some frames due to compression for web use, but you should still get a feel for the quality of the game; there are some minor visual glitches but I see no point in fixing them until all in-game features have been added; coders will understand what I am talking about!)

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