What is Allegro? Here is the brief description from its website.

Allegro is a game programming library for C/C++ developers distributed freely, supporting the following platforms: DOS, Unix (Linux, FreeBSD, Irix, Solaris, Darwin), Windows, QNX, BeOS and MacOS X. It provides many functions for graphics, sounds, player input (keyboard, mouse and joystick) and timers. It also provides fixed and floating point mathematical functions, 3d functions, file management functions, compressed datafile and a GUI.

Links to websites with information on Allegro and game programming using Allegro
 
1. allegro.cc

2. allegro.cc forum
3. Allegro HOW TO    

4. Allegro Newbie Tutorial
5. Introduction to STL programming with Allegro
6. The Allegro GUI Clinic
7. Gillius's Programming - Allegro Tutorial
8. Allegro Tutorials
9. Allegro WebRing
10. Allegro Game Programming
11. How to do 3D with Allegro
12. CCPS Solutions Articles
13. AllegAVI
14. AllegroFont Lib
15. Codes: Allegro Tetris Clone
16. Allegro Wiki
17. Allegro SpeedHack
18. Eric's computer games
19. Daniel Harmon's games
20. Bob's packed programming page
21. LexGui
22. DLG v0.43 - a DIALOG editor
23. A programming site by Charlie Restivo
24. Pixelate game programming magazine
25. Allegro category in DevPaks.org
26. Allegro Game Development Network
27. James's Game Programming Page
28. Miran Amon
29. CodeGuru's article on Allegro
30. Puyo's Page
31. Using Allegro with Visual C++ - How to Get Started the Easy Way


Downloads

1. mytitato version 0.0.1 - (File Size: 462 KB) source codes and program of a simple game Tic Tac Toe which uses Allegro 4.2. Code::Blocks project included. Also bundled in this package are several tools: grabber.exe, exedat.exe and upx.exe which are used in the project.

Contents of the readme.txt
Project: MyTiTaTo, a simple Tic Tac Toe game for 2 players.
Version: 0.0.1, a simple playable version.

Right now it is for two players, no AI, no sound effects or animation
It simulates as close as possible how two players play on paper.

Program Notes
==========
1. This program has only one C++ class.
2. Shows how to use a Windows resource file (.rc) with an Allegro application.
3. The resource file contains data so that we can use a customized icon
   for the program and also embed version information into the exe file.
4. Shows how to use html help in an Allegro program.
5. Shows the use of bitmaps in data file.
6. Shows how to use a data file and append the data file to the exe program.
7. Shows how to use a double buffer to avoid screen flicker.
8. Shows how to get mouse position and check for mouse clicks within specified
   screen areas.
9. This program static links with the Allegro library.
10. This program also uses UPX to compress the program into a much smaller size.
11. External programs bundled with this program are:
    a) exedat.exe
    b) grabber.exe
    c) upx.exe
    These are bundled because CodeBlocks does the necessary post-build actions
    to append the data file to the exe and then calls upx to compress it.
    grabber is included because the Tools menu in Code::Blocks has an option
    to execute grabber and load the program's data file. This makes it easy
    to manage the program development all within the Code::Blocks IDE.