Minesweeper if a game included with the Windows OS,along with the other classics such as Solitaire,Spider Solitaire, FreeCell and others.
To play it on your Windows XP(other Windows OS probably have it as well,but my PC uses WinXP),click the Start button on the bottom-left corner on you screen,choose the folder All Programs,choose the Games subfolder and there you have it.
I grew up in the XXI century as well,and I still know what it is.