DOOM (1993)

The only way (so far) to get this achievement is to play death match locally with 2-4 players (guest accounts can be used). Unfortunately, if you don’t have more than one controller then you won’t be able to get this one.

I don’t know if they will make this game mode available for online multiplayer, but for now it’s local only.

Quickest way to get this is to load up a local 4P death match.
Make the time limit 15
Make the score count 25

Then just grind out 25 kills

Please note, you must manually respawn the character you kill by pressing the fire trigger.

This method is what I did for Gamepass PC version. Just plug in another controller and press RT to add it to the lobby then press RT again to ready up. You need 2 controllers to get the 25 and 100 kills.

On the listed map all you do is go through the door and on the right there will be a rocket launcher. Grab it plus the rocket ammo boxes untill you have 25 or more rockets. Now just stand in the doorway and shoot rockets at the other player 25 times.

Local multiplayer
Deathmatch

Now set the options too:
Chapter: The Shores of Hell
Map: 9
Frag Limit: 25 (Highest)
Time Limit: 5 or higher

Do the above method 4 times and you have your 25 and 100 kills. It shouldnt take you more than 10 or 15 minutes.

If you do not have two controllers (or no controllers at all), then download the x360ce program, it can emulate a controller. the first controller will be the keyboard, the second will be the mouse (you only need to assign one fire button in order to launch the map). Don't worry about the fact that you only have to use the keyboard for controller 1, you will be able to control the view with the mouse for the first player, even though it is supposedly the second player.