How to turn DOOM into a tower defense game

Step 1: Obtain the chaingun

This is self explanatory. Regardless of how many secrets you search for, this shouldn't be too hard.

Step 2: obtain the turret attachment for the chaingun.

This modifier is the crux of our overpowered strat.

Optional: achieve mastery on the turret attachment.

This is not technically required to make the strategy work, but significantly boosts its effectiveness. Mastery requires you to purchase both upgrade for a total of 9 weapon points and kill 5 demons in a single turret deploy 5 times, in that order. This is easily achievable on any mission. The mastery significantly reduces the speed the chaingun overheats at to the point that it may as well not overheat.

Step 3: obtain the "Rich Get Richer" rune

This one may be tricky. In Lazarus labs. Play through the mission until you see a room with a glass door to your left with a rune stone inside it. Break the vent in the middle of the floor in front of the door to get into the room. Complete the challenge to obtain the rune. Optionally, you can get mastery on it to make the strategy easier, but its not as essential as the chaingun mastery. The rune removes ammo consumption if you have at least 100 armor (75 if you have mastery).

Congratulations! You now have everything you need to pull off the strategy

Congratulations! You now have everything you need to pull off the strategy.

Step 1: get 100 (or 75) armor:

This is the hardest part of the actual strat. There is a rune that makes demons drop armor when glory killed, which is mighty useful here.

Step 2: find a good camping spot

Any area where you can see and shoot at all oncoming demons in front of you will work.

Step 3: activate turret

Hold down attachment button.

Step 4: hold down the fire button

Step 5: pick a demon

Step 6: look at it until it dies

Step 7: repeat step 6 until room is cleared

Congrats! You are now playing a tower defense game until you lose rich get richer benefits.

Getting hit by a pinky or spectre will kill this strat since they do a ton of damage. I mention them specifically because they can sneak up on you with surprising ease. Make sure to kill them as quickly as possible.

Imps aren't a huge threat individually, but can kill this strat if you get hit by too many fireballs or one sneaks up on you.

Revenants are a similar story to imps, but are more of a threat due to significantly more health.

Hell Knights, mancubi, cacodemons, and lost souls aren't a threat if you see them first.

Hell Razers can be a threat if you don't target them fast enough.

Barons of Hell should be killed a quickly as possible due to their insane health pool and and fast speeds.