McGonigal chooses to use the phrase engage in games instead of play games. How does each phrase communicate a different tone? Why might McGonigal have chosen the phrase engage in games?

This question refers to the text Reality Is Broken: Why Games  Make Us Better and How They Can Change the World by Jane McGonigal

McGonigal chooses to use the word engage games instead of play games because this activity went beyond just playing, it was really something done for needed.

Explanation:

 Let's start directly with the following quote:

"The plan adopted against the famine was to engage in games one day so entirely as not to feel any craving for food ..."

We can clearly see from these lines that the author's goal was not to play for fun and without worries. It was something that had to be done to combat famine.

She had to really get involved in this activity so she could forget about hunger.

That is the reason why the author decides to choose these words.

they bound logs together and built a raft. enkidu steered it down the great river. gilgamesh carried humbaba's head.