SkillGrid - new AGA game in the works

I have about 100 kB of RAM and 4 kB of floppy space left, and I'm trying to come up with something to use them and make the game better before releasing it.
One of the options I'm considering is adding a little sub-game based on this dot-matrix engine I wrote a few months ago:

https://www.youtube.com/watch?v=mB6wgJbj0Gg

I've been itching to make a game with it for a long while, but I never came up with an idea that convinced me. This really feels like the proper occasion to use it.

For the tech geeks...
This engine for AGA Amigas displays 4 colors (+ background color), has chunky dots (i.e. each dot can be written or read with a single byte memory access), and doesn't require any chunky-to-planar conversion (i.e. it's almost as if it were a hardware native video mode). I have a few variants of it, including one that has non-dotted background graphics.

For the curious ones...
Computer simulations of pinball dot-matrix displays fascinated me ever since I saw Pinball Fantasies. In fact, I've faked them in a couple of my games (an unreleased game and the old versions of MeMO) and even based a whole game (Huenison) on them. Less than one year ago I pulled my A1200 out of the closet and powered it up again. It had been many years since I had coded something for it, and this is one of the results of the experiments I started doing on it.

It's time for another update...

Major piece of news: as you can see from the pictures kindly provided by RGCD and Tony Aksnes, SkillGrid has been adapted to the Amiga CD³²!





Other changes:
* added missiles;
* changed the way the MULTIPLIER cell deactivates;
* changed the behaviour of the REPAIR and DAMAGE cells in Music Mode;
* made timer tick when 10 or less time units remain;
* refined gameplay parameters;
* multiplied points by 5;
* added pause;
* added 4 new UFO types;
* touched up some graphics;
* made screens transitions 100% smooth;
* made many internal improvements/optimizations/fixes;
* improved/adapted/extended manual.

Note: the sub-game idea based on the dot-matrix engine mentioned previously had to be dismissed due to lack of space.

@saimo

awesome for Amiga CD³² users

New video preview... and there's a lot to see in it! In fact, it shows many of the changes from the (massive) changelog below.

https://www.youtube.com/watch?v=jBHGjaJRlhE

CHANGELOG
* Changed music from 14-bit mono to 8-bit stereo.
* Improved audio tracks mixing.
* Added mothership fight.
* Added asteroids.
* Added DOUBLE FIRE cell.
* Added screen flashing when the NUKE cell is caught.
* Made NUKE cell cause a 1 unit damage to bosses.
* Improved destruction sound effect for NUKE cell and boss.
* Made various changes to the effects of cells.
* Restricted the types of cells to a selected subset during the first 30 seconds of play.
* Made the boss weapon mouth and bolt flicker to give the former a more dangerous feel, and make the latter easier to see.
* Improved transformation of bosses.
* Added a little graphical effect to the boss.
* Changed pitches of cell catch sounds (making them more distinguishable and shorter).
* Added speech warnings.
* Added looping to alarm sound.
* Increased the minimum scrolling speed so that it can never become (dangerously) too slow.
* Changed title / pause / game over screens.
* Made various other improvements/optimizations/fixes.

(So you've spotted the RGCD logo in the title screen and you're wondering if that perhaps means that the game is going to be released also as a cool physical package? Hush hush... don't tell anyone, but rumor has it that such a package will contain the floppies for Amiga 1200 and Amiga 4000, as well as a CD for Amiga CD³²!)

https://www.retream.com/SkillGrid

@saimo
Looks very good :)

@ 328gts tommysammy

Thanks!

@saimo
I made it public at a1k.org

@tommysammy

Very nice of you - thanks a lot!

@saimo

sweeeeet

Want to read a cool preview from someone who tried the game first hand? Just check out this cool blog article by Tony Aksnes!

By the way, work on the packaging is about to start, so hopefully you'll be able to get the game from RGCD Q1 2019

Great slick looking game Saimo, can't wait to see what you work on next (Amiga NG game possibly?)

Meanwhile going to did through your dev log https://retream.itch.io/skillgrid/devlog

@invent

Quote:
Thanks :)

Quote:
No, sorry, I don't have plans for other Amiga NG games. My future projects are all for the classic Amiga and the C64 (details on my Patreon page, and I don't even know if I'll ever manage to get any one of them done.

Quote:
Oh, I appreciate that a lot! Thanks.
Tomorrow I might publish another update. The game is basically done, and I've started making the packaging artwork.

Nice to continue the Classics and into C64 "QUOD INIT EXIT II" for C64 looks rather interesting :) Best of luck with whatever you do next.

guys just a reminder that Simone has a
patreon account

@invent @328gts

Thanks!


@all

Great news: development is complete! Now work on the packaging for the RGCD release has started.


Click to enlarge.

CHANGELOG

* Added skull baddie.
* Added milestones.
* Fine-tuned gameplay parameters.
* Improved boss and mothership AI.
* Added blinking halt sign.
* Added danger warning for when the shield is really low.
* Redrawn a couple of UFOs.
* Improved asteroids graphics.
* Made various optimizations/improvements/fixes.

https://www.retream.com/SkillGrid

@saimo
Great news, download version available too?

@tommysammy

Yes, it will be made available at the same time as the physical edition.

If you're curious about how the scrolling works, this video is for you:

https://www.youtube.com/watch?v=7wjSqNVRV1w

To fully appreciate it, please read the technical details below. Please note that some knowledge of the Amiga hardware is required.

Given that about 80% of the RAM that the standard Amiga 1200 and CD³² are equipped with is allocated for music (which is not standard tracker modules, but conceptually MP3-like as detailed in this article), SkillGrid uses a number of tricks to fit all the rest (code, graphics, and sound effects) in the remaining memory. Some of them are shown in this video.

The background is made of three parallax-scrolling layers:
* the bottom layer consists of a bitmap that is much taller than the screen;
* the other two layers are rendered dynamically by blitting graphic tiles as needed - this is necessary to have graphics change all the time and, at the same time, allows virtually endless layers at the small cost of the memory taken by the tiles graphics;
* the two layers are not buffered, but are just slightly taller than the screen: the incoming tiles are rendered in the out-of-screen areas, thus hiding the drawing process to the eye (with buffering, almost twice the RAM would have been needed, instead);
* all the layers are wrapped around in real time by the Copper (as explained in the next paragraph); this mechanism allows the layers to occupy exactly the amount of RAM needed by the graphics (i.e. no extra RAM is required for the twin copies otherwise necessary to smoothly restart scrolling when a layer has scrolled entirely).

The layers wrap-around trick is implemented like this:
* the line that a layer starts to display from at the top of the screen can be any (for exampe, if a layer is 300 lines tall, any line between 0 and 299 can be the line displayed at the very top of the screen); this is obtained by telling the Lisa chip (through the BPLxPT registers) that the bitplanes of the layer start at the addresses corresponding to the chosen line;
* if/when the bitplanes of the layer are entirely displayed but the screen has not been entirely redrawn yet, the Copper writes on the fly the addresses of line 0 to the BPLxPT registers (for example, if the topmost line was 280, when the 20th visible line of the screen has been drawn the bitplanes bottom has already been reached, but there are still 256-20 = 236 screen lines to draw, so the Copper brings the bitplanes addresses back to the very beginning; the result is that the bottom of the bitplanes is visually followed by their top);
* therefore, the Copper has to continuously wait for the screen line(s) where it is necessary to reset the BPLxPT registers and then perform the writes; normally only one layer per line needs to be wrapped around, but, depending on the position of the layers, occasionally two or even three layers end on the same line and thus have to be wrapped around at the same time;
* the Copper code (Copperlist) that performs such operations is generated by the CPU every frame after the screen has been drawn entirely, according to the current scrolling position.

In the first part of the video:
* the blue layer is the bottom layer (layer 0);
* the green layer is the middle layer (layer 1);
* the red layer is the top layer (layer 2);
* the lines marked with T0/T1/T2 indicate the top of layer 0/1/2;
* the lines marked with B0/B1/B2 indicate the bottom of layer 0/1/2.

It is worth noting that since the tiles of the top layer are hexagons, they are vertically shifted by half a hexagon every other column. As a consequence, the bottom row tiles in the odd columns actually need to have the upper half blitted at the bottom of the layer, and the bottom half at the top of the layer. Due to the fact that the layer is made of two bitplanes, up to four separate blits might be necessary to render a tile.
In the second part of the video, these tiles are those that are crossed by the horizontal line that marks where the layer wraps around.

Little Christmas gift: preview of the inlay that will grace the RGCD package!


click to enlarge

The package will include a CD, a nice manual, a few surprises and, optionally, also two floppies. The CD can be used to play the game on the Amiga CD³² and also to install the game on the Amiga 1200/4000; moreover, it contains also the ADF images of the floppies.
To be released (hopefully) in Q1 2019.

https://www.retream.com/SkillGrid

@saimo

inlay looks awesome! can't wait to see the manual