POSTAL

A very easy achievement that only requires you to press one button.
By default, the suicide button is "K", but you can change that in the control settings.
After pressing the button, the protagonist will shoot himself in the head, and you will get the achievement.

1. Start the game
2. Single Player --> Challenges --> The Gauntlet
3. Play till you reach "Home cookin" (the train station level)
4. SAVE THE GAME!!!
5. Keep shooting your Auto Shotgun, pick up all the shells scattered around the map (a few packs have 500 or 1000 shells in them, not very sure how much BUT some have only 10)
6. After picking up all the ammo packs and shooting out all the shells you may quit to the main menu
7. Load the save that you made
8. Repeat step 5 about 35-50 times, every attempt should take 8-12 minutes if you focus, one attempt does around 25,000 to 30,000 bullets shot if you pick up all shells

From 100,000 shots to 1 million this should take about 5-8 hours, yes this is very boring but you can also leave the game in the background while Dude is shooting his SMG, it'll take longer but atleast you dont have to focus on the game and do your other plans

One of the easiest achievements in the game, without which you can't continue.
Simply shoot the enemy to death and you will receive the achievement.

All you have to do is not dodge the rocket.
In most of the levels you can meet rocketmen. After one of them takes a shot, all you need to do is to get hit by the rocket.

Rocketman:

While using a virtual machine of Linux is possible, it should be noted that playing the game on a Steam Deck will also trigger this achievement.