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Open Invaders
(c) 2006-2007 Darryl Lecount/Jamyskis
This game is released under the General Public License Version 2. More details
can be found in the accompanying license file.
Lead programming, design, sound by Darryl LeCount. Graphics by Amber Adams and
Darryl LeCount. This game was written using the Allegro library by Shawn
Hargreaves. The code includes elements of the PMASK collision detection library
by Orz.
PLEASE NOTICE THAT THIS GAME IS STILL IN DEVELOPMENT AND IS NOT CONSIDERED TO BE
FINISHED OR STABLE!
Installation prerequisites
==========================
To compile from source, you require:
* Allegro 4.2.1 development libraries
* DUMB 0.9.3 development libraries
Please note that your Linux distribution may not have a DUMB package complete
with Allegro support. If you get an error during building that aldumb.h could
not be found, you'll have to download and build it yourself from
http://dumb.sourceforge.net. Also, to the best of my knowledge, Allegro 4.2.0
will *not* work with this game. Sorry.
Under Linux, compiling from source should be as easy as:
./configure
make
make install
Make sure you have root access for the last bit. PMASK is included in the
archive.
If you prefer to run the precompiled binary version (Linux or Windows), just
unpack the archive to a folder of your choice and run the open-invaders file
(under Linux) or Open Invaders.exe (under Windows).
There is also a self-extracting Windows installer, which will install shortcuts
in the start menu and on the desktop.
Instructions
============
When the title screen first appears, press any key or the first button on your
joypad/joystick to bring up the title menu. From here you can opt to begin a
game, see who was responsible for this wonderful game or change the options.
If you decide to change the settings under options, you'll find that you have a
choice of five difficulty levels and the possibility to adjust the sound effects
and music. You can also redefine the keyboard controls should you so wish.
By default you use the arrow keys to move left and right, and left shift key to
fire. Shoot all the enemies, avoid their shots, kill all invaders to progress to
the next of 14 levels. Shooting the UFO gives bonus points. The shields provide
limited amounts of cover. You get an extra life for every 20,000 points. As
you'll discover from the ending, playing on a harder difficulty level is in
your best interest.
You can also use a joypad/joystick - if you have two or more plugged in, it is
the first one listed in the joystick control panel (Windows) or the device
located at /dev/js0 or /dev/input/js0 (Linux).
You can return to the title screen by pressing Q (unless redefined).
If you wish to do an emergency exit from the game (in case the boss is coming)
you can press CTRL+C. To create a screenshot, press CTRL+S.
The game will generally automatically start in fullscreen mode, unless there is a
problem with this, in which case it will start in windowed mode. You can force
either mode by starting the game on the command line with the arguments -w (for
windowed) or -f (for fullscreen). You can switch between windowed and fullscreen
modes in-game and on the title screen by pressing CTRL+F, ALT+ENTER or selecting
the option from the options menu.
To add to the fun, the game has 35 unlockable features. Most are fairly easy to
unlock (get a certain amount of points, reach a certain level, complete the game
etc.) but the rest will have you scratching your head for ages to come. Have
fun! You can see what you have unlocked (and access the features) by going into
the options menu from the title screen and selecting "unlockables".
Tools used in making this game
==============================
This game was made using 100% free and open-source software (FLOSS):
Ubuntu Linux, Anjuta, Code::Blocks, GCC/MinGW, the GIMP, Audacity, NSIS,
Allegro, OpenOffice.org, TileStudio.
FAQ
===
Why this game?
Because it was fun to make and at the time I thought there was no known clone of
the original Space Invaders on Linux. I know better now, but it's still good
fun.
When I run the game in the console, the game reports "corrupted double-linked
list" when I exit.
This is a known bug, though I'll be damned if I know what's causing it. It's
not fatal anyway, and I'll hopefully have it pinned down by the time the game
goes beta. As I see, the error depends on the version of GCC being used. As of
8th June 2007, I'm not seeing this anymore, so the 4.x.x series of GCC doesn't
seem to be experiencing this problem.
The collision detection is iffy.
Actually the collision detection between the aliens and projectiles is pixel
perfect. The collision detection between projectiles and shields however relies
on a series of hacks that have provided the best solution thus far but are not
perfect. I'm working on it.
The game has 100%/very high CPU usage.
There are several explanations for this. The first is that I simply haven't got
used to the concept of CPU yielding in C++. However, the code does contain some
elementary checking. The problem is that the Linux version of the game does not
support hardware graphics acceleration and with the 50-60 sprites being thrown
around at any one time, it's understandable that a 1GHz machine would be the
absolute minimum. As Windows Allegro does support hardware acceleration, the
requirements there are a fair bit less. I have tested the game in fullscreen
using top in another tty and the game never goes above 71% on my Athlon 2400,
with Xorg running. It should be stressed that this is not a problem with Linux,
but with the Linux version of Allegro.
I've found a bug!
Tell me at the contact details below.
The source code is a bad example of programming.
First of all, I'm a beginner, so don't berate me too much. That said, there's
parts of the code I don't like, simply because they feel too much like hacks at
times. I'll look at this in time.
The game accused me of being a cheater! I didn't do anything.
Please send me your hiscore or hiscore.dat file. Under Linux this is located in
.openinvaders in your home directory, under Windows in the game's data
directory (usually c:\Program Files\Jamyskis\Open Invaders\data) by default.
The game accused me of being a cheater! Why shouldn't I be able to edit my
highscore file?
Because I am eventually hoping to have an net-based highscore table, and
cheaters aren't welcome there.
I didn't get a completion bonus when finishing the game!
I'm guessing you unlocked level 2 or above and then attempted to start from that
level. To get a completion bonus you need to begin the game from level 1.
What's the top score you've managed when playing honestly?
66,300.
Contact me
==========
You can view more of my work at http://www.jamyskis.net
If you have any questions, feedback, bug reports etc. please forward them to
darryl@jamyskis.net, my Jabber account at jamyskis@jabber.org or ICQ 213921710.
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