Two-player minesweeper game.
MSN Messenger, later known as Windows Live Messenger, was an instant messaging client made by Microsoft. It was first released in 1999 and remained in service until 2013, being ultimately discontinued in favour of Skype which Microsoft had acquired in 2011.
One of the features of this service was the games and applications. This would allow for you and the other person you were chatting with to play or collaborate. It included applications like Whiteboard, which allowed users to scribble together, or Remote Assistance that would let a user take control of the other’s computer. It also had about a dozen games like Bejeweled, Checkers or Tic-Tac-Toe.
The most addictive game for me and my friends at the time however ended up being Minesweeper Flags. It was a twist on the original Minesweeper, with two friends playing against each other, and instead of avoiding mines your task would be to find them. It was turn-based and each player could keep on playing until they found no more mines, with the winning condition being finding 26 of them.
I enjoyed it so much that I ended up cloning it. I used C and Allegro, a popular game development library at the time and made ample use of its Atari-ST style GUI system, theming it with agup. Like the original it was a two-player game, this time allowing hot-seat play. It also had a rudimentary computer opponent if you found yourself alone needing your minesweeper fix.