Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nd4/4. Nxe5/4...Qg5/5. Nxf7/5...Qxg2/6. Rf1/6...Qxe4

6...Qxe4+
White is completely lost. Black plays 6...Qxe4+, which allows for two options.

The worse of the two options doesn't seem the worst, but 7. Be2 allows the smothered mate 7...Nf3# where the bishop is pinned.

Therefore White must give away the queen with 7. Qe2 and play on without that queen.