Xenion is an ambitious scrolling arcade game in the vein of the arcade game Xevious although honestly I think this version is more complex. The basic premise is that you are attacking an evil alien race in their own solar system, flying between 4 planets (which you can see above in the 2nd intro screen). The game runs in a 4 color mode, but makes great use of it's color palette (black, blue, green and white), including widely varying terrain (out in space, over oceans, alien cities, cratered landscapes, etc. of which you can see a small portion above), plus 27 different types of aliens, a variety of ground based aliens and alien structures to shoot (tanks, force field generators, radar stations, etc.) There are also some pickups for the player - an "E" to charge up your shield energy, and something that looks like a key that gives you a smart bomb. The game is operated by a single button joystick, with the SPACEBAR serving as your smart bomb button (which destroys most aliens on the screen - motherships and force fields excluded). You can also pause the game at any time, and each time you die or complete a solar system, the game will pause until you hit the joystick button to resume play. The game also features auto-fire on the joystick, so it's not technically a button masher. It does feature a fairly advance graphical layering system internally, similar in principle to what Nick Marentes does on his current games (although using a slower algorithm).
Xenion has a bit of history behind it, from what I can gather. The original Diecom ads, which picture the game you see above, also mentioned that there was a Coco 1/2 version that ran off of tape or disk (which makes some sense as it is a 320 x 200 4 color game on the Coco 3 which has some "decoration" on the right side of the screen... it would likely have ran as a 128 x 192 4 color game on the Coco 1/2 without the decoration). However, no one I know of has ever seen that version; if you have, please email me. It is quite a fun game, although it ran a little slow.
Which brings me to some modifications that I did at the end of November in 2019 as an experiment, using the debugger in MAME to track where some of the main drawing routines were. I ended up making 3 enhanced versions of the game - a 6809 enhanced version that added some mini-stackblasting, a 6309 version using the TFM command instead of stackblasting (which is faster), and a 6309 native mode version with stack blasting, which literally runs around 2-3x faster. All 4 versions (including the original) can be downloaded below. If you have a 6809 based Coco 3, you can play the stock original version or the mini stack blast enhanced version which faster. If you have a 6309 in your Coco 3, you can try all 4 speed variants and pick the one you like best. (I will mention that both versions of the manual - Diecom Products and REMCOMS - are both on the archive as well, with the REMCOMS one have much more information about the game.
Author: Michael Duncan
Publisher: Diecom Products (1988, written in 1987), later REMCOMS in 1993
Requires: Color Computer 3 (See note above), 128K RAM, 1 or 2 joysticks
Download Xenion here. (ZIP file containing 4 DSK images: XENION.DSK (Original Version), XENION8N.DSK (optimized 6809 version), XENION3E.DSK (6309 TFM instructions added), and XENION63.DSK (6309 TFM and 6309 Native mode enabled)).
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