Saturday 24 September 2022

Xevious

 After about 6 months of inactivity I've been motivated again to work on a retro project.

A few days ago I saw a post about a YouTube video called "The History Of Xevious"

Xevious gameplay

After a discussion about the video on a shmup group I was also made aware of another cool video on the secrets of Xevious. I discovered at least one sol tower I wasn't aware of, and also a picture of a map that showed all the sol towers in (the MSX version of) the game.

A map of the MSX version, which is very close to the arcade version

Xevious is my all-time favourite arcade game and therefore my "holy grail" of reverse-engineering and transcoding/porting projects. I started on this back in March (see the previous post on the Ghidra disaster) but after RE'ing all the "low-hanging fruit" it stalled as I got busy with Real Life again.

Xevious is probably the most ambitious RE project I've tackled to date. It has no less than three (3) Z80's running in parallel; one for the game, one for the inputs and graphics, and one for the sound. And after working on the code for a while, it's apparent that it's going to be a real challenge.

I picked it up a few days ago, and after getting familiar with the code again, I've made some progress. It's still slow going, and it's going to be a matter of just chipping away until things fall into place. It's not something that I expect to be able to finish in a matter of weeks or even a few months. Or maybe not ever.

And if I do ever finish, I'm not convinced it lends itself to the transcoding process either, especially on a target with one processor. This may end up being more of a port than a transcode, but time will tell.

From time to time, when I want a bit of a break, I may post a few entries on the structure of the code, or interesting aspects of the code etc.

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