In the original script and the official movie novelization by Peter David, Megatron actually saves Optimus Prime from Sentinel Prime. Instead of being executed, Megatron offers a sincere truce, stating he is tired of the war and wants to take the remaining Decepticons back to Cybertron to rebuild. Optimus’s Mercy:

Rated PG-13 for intense sci-fi action, violence, and destruction.

"Transformers: Dark of the Moon" received mixed reviews from critics but was a commercial success. The film grossed over $1.1 billion at the box office worldwide, making it one of the highest-grossing films of 2011.