Wasteland Remastered

General Argent rank is achieved at character level 131 and requires a total of 8,719,360 experience. Yes, you read that right. Playing the game naturally, you won't come anywhere close to this. Once the game is complete, you can either start killing enemies in Las Vegas for an entire weekend, or use the wonderful Play Anywhere feature this game offers and a little help from a macro tool to have it done for you on your PC.

Get on the roof of Ugly John's hideout. You can get to this location by walking into the alley next to the building and then using a rope to get to the roof. Up here, you will be able to earn unlimited experience by simply walking up and down the right side next to the glass. You will continually pass Perception skill checks, noting the enemies below, and earn experience every time.

Now, the trick to automating this is to download AutoHotKey, a simple macro program. Once you have that installed, you can create a new macro by right-clicking on your computer desktop. In the box that pops up, paste the code below and save your script as a file on your computer desktop. Then, right-click on the file and choose "run script." Once you have the script running, load up Wasteland Remastered, put your character in the middle of the glass, and then press F1 on your keyboard. This should begin the script, and you'll see your character move up and down extremely rapidly on its own.

Going from Level 1 to Level 131 for this achievement will take about 20 hours of idling, but I'd suggest stopping the script with F2 on your keyboard and saving every so often just in case. I found that the game got confused and my character continued to move constantly even after the script stopped, so you may need to load the save you just made to start fresh and don't forget to run the script in the background again before trying to restart it!

Here is the script for the macro:

There might be faster options of creating macros to continually camp somewhere or something else, but this is the first trick I found (thanks to lazygammer for posting it)and I ran with it. I left my game running for 20 hours overnight and when I was at work the following day and I got all the achievements once I applied my levels. If anyone has faster locations and the accompanying macros that get the job done, feel free to comment and let us know.

https://www.autohotkey.com/

If you want to grind this out, you can take your party into the alley between the derilict building and Ugly's Hideout on Hubcap street. Once inside, use a rope to climb up on the roof. There will be one enemy to kill.

One you have that taken care of, walk back and forth along the skylight to get a message saying something like, "You could probably break this to ambush those inside." Every time you walk past a window, it gives you experience and levels up your perception skill. You can gain several levels in just a couple minutes. It even works after you have cleared out Ugly's hideout! (although, I don't know if breaking the glass will void the glitch).

After getting enough XP for a character, you can hit to radio into Ranger HQ and they'll promote you up through the ranks... which you should definitely know by this point! General Argent rank is the hundred and thirty-first rank in the promotions (for the first level of it, at least), and requires a staggering 8,719,360 XP!

This requires some significant grinding, which is part and parcel for Wasteland. As noted in my other rank solutions, you get more XP when killing things with melee, so the best way to grind some of these levels out is by decking your crew out with some good melee weapons.

Notably, Base Cochise is a great place to grind out XP. Even though you *can* keep playing after dealing with it, the Base and its associated mobs will be gone, so I strongly recommend making a save just before the last few steps in Cochise and starting from there for the level grind rather than playing on. If you're geared well enough, you'll easily be pulling in many thousands of XP per melee kill.

Edit: Stolen from comments in the other solution, this gem from FranticRed:
And from TechnicallyCalm:
I can confirm that I spent a good many hours getting from 5m to 8m harvesting for the last rank, so camping for levels (particularly early on) might be a good way to reduce risk in the game overall.

For this and the other rank achievements:

Rank - Level - XP
Corporal - 5 - 10240
Sergeant - 12 - 67584
Lieutenant - 30 - 445,440
Captain - 45 - 1,013,760
Major - 60 - 1,812,480
Commander - 103 - 5,379,072
General Argent - 131 - 8,719,360

Edit: Turns out that the list I was going off of at fandom.com was wrong around Captain and afterward! I've adjusted them here, and the one at https://wasteland.gamepedia.com/Desert_Ranger_ranks_(Wastela...) matches, for anyone interested in the complete list.

Since none of the guides mentioned this yet, I figure I'd mention another spot to idle experience at the same speed as Ugly's Hideout but without any macros that need babysitting, so it works better on Xbox at least.

Camping in the lake is still the fastest method but since you'll need to restart the macro it's not entirely automatic.

Head to Vegas and go upstairs in Spade's Casino. Lockpick works without triggering hostility. I can't confirm if TNT or strength trigger combat.

When upstairs you'll see a hatch. Break into the room, kill the lady with the Uzi and use a rope to get down the hatch.

You'll reach an extremely unremarkable crawl space under the casino. At the top left are rocks that trigger a Climb check just by walking into them.

Strap down the joystick to walk up into the rocks and plug in your controller in so it stays active. Now you can go to sleep, work or school and get experience equal to the Ugly's Hideout skylight, plus the macro won't need to be restarted constantly so it's fully automatic.