Outpost in the Dragon's Maw

Outpost in the Dragon's Maw is a retro style Match-3 Tower Defence game for the Uzebox open source game console, a bit of 8 bit madness involving an ATMega 644 and a bit of electronics to get it producing a video signal and accepting input from an SNES controller. Thanks to emulation, you may also have a few rounds of it right within your browser!

If you want to play right away, proceed here (note that it needs a computer and a keyboard, it won't likely play well on a phone).

After the discovery of a lush new continent, you are tasked with establishing the first settlement on its shores to exploit its riches. This all goes well until mysterious disappearances start to surface along with uncertain sightings of large flying creatures...

Controls

You can navigate the cursor with the arrow keys in the emulator, use Space to select or deselect items, and Enter to switch between menus.

How to play the game

The goal is building up your defences to guard your settlement against the ever increasing onslaught of dragons by matching items on the playfield. Move at least three of them adjacent in a row or column to make a match.

• Stone towers are able to shoot at dragons in their close proximity (adjacent tiles including diagonals).
• Wooden ballista towers are able to shoot diagonally to any distance. They are unable to shoot directly above them.
• Cannons shoot explosive cannonballs forward which deal splash damage covering nine tiles.
• Markets buff the four directly adjacent tiles, so towers or cannons there deal more damage. Their bonus if multiple markets are adjacent to a tile doesn't stack.
• Gold gives you money to spend on expanding the settlement or to get more work done in a month.

The options in the Gold menu:

• End: Ends the month early. Up to a month's worth of swaps can be carried over to the next month if using this option.
• Pop: Get one more population. Every 10 population gives an extra swap for the month! This option gets more expensive if used excessively.
• Swap: Get an extra swap. Using it multiple times within the month makes it more expensive (there are limits how much your people can work!).
• Anyswap: Swap the tile where the cursor currently is with any other tile on the field.

While playing, knowing the followings may also come handy:

• Large matches and combo matches also earn you gold.
• Matching five or more tiles will jump a level (for example matching five small Level 1 towers would result in a Level 3 tower).
• Any item can be dropped at the cost of a swap by holding Select on it for about a second.

Technical quirks

The Uzebox console is built around an ATMega 644 chip which has only 64Kb of ROM (60Kb usable, the upper 4Kb is the bootloader) and 4Kb of RAM, running at 28.6MHz, however it also has to generate the video signal directly (no video hardware at all, not even that much like in an Atari VCS).

This game although might not look as impressive as Flight of a Dragon at glance, it has a substantial trick of its own: In the dragon waves, it shows off such amount of sprites no other game on this platform pulled off before. This is achieved by a new video kernel which utilizes a line-buffer, compositing sprites onto the display line in the horizontal blanking (so in fact works quite similar to a video chip with real sprite capability such as the Commodore 64's VIC-II), paired with a decent sprite multiplexer.

The drawback of this video mode is that the background tiles (the towers and the town) are very costly having to be generated by AVR assembly code on the fly, which makes them taking half the ROM space. Not too much left for the other kinda important bits to make a game!

Free source

The game and its art is released under General Public License Version 3 or Creative Commons BY-SA Version 4.0, as usual for games released for the Uzebox console. Feel free to play around with it, hope that tricky mess is at least as enjoyable as the game itself (if you like that sort of stuff)! ;)

You may look around in the game source on its Git repository.