The defenderlr plugin

This plugin for Defender and Stargate is adapted from the original by oomek here and works with MAME v0.227 or newer.

It should work with whatever you have configured to act as a joystick with no configuration.

I know someone asks about defender every few months, and I've been meaning to get this working for me for a long time, but I've just now gotten around to it. This makes the game way more playable, though I still prefer Defender II for the 2600. The enemies in the arcade original are pretty devious and dodge your laser gun like alien ninja.

A note about the implementation. I tried to avoid writing to memory by detecting the facing of the player and triggering the reverse button, but it didn't work. While I was able to successfully detect the facing, triggering the reverse button didn't reliably work and I couldn't figure out why. So I fell back to the behavior in the original plugin of writing to memory. There doesn't seem to be any side-effects from casual observation.

Anyway the fact that you can do this with no modifications to mame is pretty cool.

Configuring MAME

1. Can you launch Defender and Stargate in MAME? (mame.exe defender and mame.exe stargate)

If not, you need to find the correct version of the "defender.zip" and "stargate.zip" ROM files for your version of MAME and put them the \mame\roms\ folder. (ROMs not provided here.)

2. If you don't already have one, create a "mame.ini" file using the mame -cc (create config) command.

Open it in Notepad and verify that it contains plugins 1 (enabled).

#
# SCRIPTING OPTIONS
#
autoboot_command
autoboot_delay      0
autoboot_script
console             0
plugins             1

Check the inipath and pluginspath settings so you know where to put those files so MAME can find them.

For example, inipath .;ini;ini/presets indicates that MAME will look for .ini files in three folders \mame\, \mame\ini\, and \mame\ini\presets\.

#
# CORE SEARCH PATH OPTIONS
#
homepath        .
rompath         roms
hashpath        hash
samplepath      samples
artpath         artwork
ctrlrpath       ctrlr
inipath         .;ini;ini/presets
fontpath        .
cheatpath       cheat
crosshairpath   crosshair
pluginspath     plugins

3. Make a \mame\plugins\defenderlr\ folder.

Put the "init.lua" and "plugin.json" plugin files in that folder.

4. Make text files named "defender.ini" and "stargate.ini" in either the \mame\ini\ or the \mame\ folder.

Both ".ini" files should contain the text plugin defenderlr.

5. Enable the defenderlr plugin via the MAME user interface "plugins" menu.

or

Edit the "plugin.ini" file and change defenderlr 0 (disabled) to defenderlr 1. (enabled)

#  
# PLUGINS OPTIONS  
#  
autofire      0
cheat         0
cheatfind     0
commonui      0
console       0
data          1
defenderlr    1

Now you're ready to play Defender or Stargate and blast those pesky aliens.