Hearts (Microsoft, PC)

Another of the Microsoft card games, and the first one with multiplayer support. Still, it didn't quite gain the popularity of its sister games.

Debug mode
This game has a debug mode, but it's a bit harder to enable here because it requires editing the Windows registry.

Open a registry editor and go to key  (create any sub-keys that don't exist). Add a REG_SZ named ZB and set its value to 42.

After having done this, start the game and you'll be able to use the keyboard combination Ctrl + Shift + Alt + F12 to see the cards of your competitors. This was probably used to test the game engine and possibly also the AI.

Debug Menu
Like Solitaire and FreeCell, the game was rewritten for the release of Vista. Versions since then have an internal g_debugEnabled variable that when set to a non-zero value replaces the normal menu with this debug one.

Setting that variable also enables the very same block & pause modes and logging as described on the Solitaire page.