Reader laonianren wanted to know more about this game Walls and Ladders.
"Walls and Ladders" is not a game. It's just a metaphor for a conflict in which one side wants to perform some action and the other side wants to prevent it. The defending side builds a wall, and the attacking side builds a taller ladder. In response, the defending side builds a taller wall, and the attacking side builds an even taller ladder. The result of this conflict is that the defending side constructs an ever-more-elaborate wall and the attacking side constructs a more-and-more complex ladder [link possible NSFW], both sides expending ridiculous amounts of resources and ultimately ending up back where they started.
There is a closely-related metaphor known as an arms race. In an arms race, each participant wants to be the most X, for some property X. An arms race tends to be all-attack, whereas wall-and-ladders tends to have one side attacking and the other defending.
Since many conflicts can be phrased either as an attack-attack scenario or an attack-defend scenario (some defenses may include counter-attacks), I tend to get the two confused. Notice, for example, that my arms race article contains mostly walls-and-ladders scenarios; for example, a case where one side wants to terminate a process and another wants to prevent it from being terminated. On the other hand, my wall and ladders example was really more of an arms race, with both sides wanting to take control of the screen.
Depending on which group you work with at Microsoft, you may find a preference for walls and ladders over arms race, probably due to the same sensitivity to military terms that led to the War Room being renamed Ship Room. (I seem to recall that there was a lawsuit that among other things alleged that the fact that a Microsoft project called its daily meeting room the War Room was proof of Microsoft's evil essence.)