Team Fortress 2

The longest and most consuming to grind but here is what you should be doing:

1. Download the map from this site: https://tf2maps.net/downloads/mvm-achievement-grinder.12519/.
2. Boot up the game after completing your map download and files.
3. The name of the map should be: mvm_achievementgrinder_rc1.
4. Do few achievements related to mvm if you can, then start upgrading all or just Engineer, wrench, and sentry gun to all max.
5. Now stay close to the bots spawn area where 11 - 22 bots spawn infinitely. Build sentry and dispenser close.
6. Type in console +attack. Now you can leave the game running for at least +30 hours.

This achievement is actually easier than it sounds, because its working even for the self-inflicted critical damage. The easiest way to get it is to go on some server together with your friend, who selects Demoman. While you are getting your ubercharge ready, he is lining sticky bombs around until RNG grants him a critical one which is easily recognizable by burning. The same second you deploy the uber on him he activates the bomb for a sticky jump, and boom - the achievement is yours.

For some reason, I couldn't get this achievement in the way its described - by killing cloaked spies. Instead, I got it by killing disguised spies, and I noticed that the achievement made progress when I killed using the Wrangler some dude who was foolish enough to disguise as a Scout, since he was running like a slug.

Remaining two kills I got on a duel map. At the top floor where I've built teleporters and a dispenser, spies are regularly coming trying to sap your buildings. Just doing regular spy checks using your Wrangler on anyone coming from the only stares leading to the floor should get the job done.

1. Download this map from Steam workshop: achievement_primecuts.

2. Launch the map and use your other dummy account.

3. Any weapons are fine, I would prefer the bat.

4. Type in mp_respawnwavetime 0 to make the grind faster to complete.

5. Stay near to where the red team spawns or your dummy account, make sure you can kill your dummy account consistently.

6. Type in +attack on console and enjoy the afk grind for 5 hours.

Sometimes, even if you set up the position correctly, its best to check as your dummy account will be launched further or to the side.