Tunnels (Doom Resurrection)

Tunnels is the third level of Doom Resurrection. The player continues toward the Delta Labs. On the way, Dr. Garrett says he is disturbed by his findings so far but needs additional information and asks the marine to look for another terminal. Sam uses her blowtorch to take down a door for the first time. After finding more information, Dr. Garrett states that the invasion has just begun and that the UAC is responsible, but that his files keep getting corrupted and he suspects that a conspiracy is ongoing. He notes that Sam's systems have highly sophisticated protection against this corruption and so it will be critical to keep her safe. The chainsaw is introduced as a weapon, and the demon first appears as an enemy.

Essentials
The last six demons encountered form a boss battle; each has a visible life bar with more HP than usual and more sophisticated attack patterns, including lunges that can be dodged.