Resident Evil: Operation Raccoon City

This achievement is a combination of all character skill upgrades, and can be obtained through Versus or Campaign. This can work for Quite The Collection achievement as well. Once you know what you are doing, this only takes about 20-25 minutes to complete.

Edit: After doing a few tests, it seems that casual gives only 2000-3000exp less than Professional does. Why work harder when you can work smarter huh? I'd say go for Casual, collect the collectibles to make that 2000-3000 a bit smaller. All you have to do is follow the guide still. I had 740 kills, with all S ranks except a D in collectibles. With 740 kills on Casual, and an S rank in Deaths, Time and Kills, I gained almost 24k exp, just a few hundred shy of it. Happy hunting everyone.

Personally, I think campaign is the best way to finish this achievement. By choosing Free Play, End Of The Line. Depending on the difficulty you choose, you'll gain more experience. The best choice is Casual for exp boosting. Professional only gives a few thousand more at best.

If you want to solo, then pick Lupo. She is OP and her ammo reload will save you tons of times. I would strongly recommend the Riot Gun, and the Samurai Edge/L.Hawk. Combined with her Super Soldier. Riot Gun will get you through most things, and the Samurai Edge/L.Hawk is devastating to Spec Op forces, if you aim for the head. Though this is all preference, other players may have their own ideas of how to go about their fights.

Go through the level as normal, till you get to the last section with Leon sniping. You'll want to kill off the Spec Ops, as they will take your zombie kills. A good way to go about this is running up to the wooden barrier they are behind, and start shooting them with the Samurai Edge/Lightning Hawk. Grenades work wonders as well.

The next thing you can do to make things easier and have more kills for yourself, is to take Leon out of the fight. Dealing enough damage to Leon in this section will make him leave the fight. Get against the wooden barrier where he is sniping at first. You can aim up and hit him with the Samurai Edge/L.Hawk. After about 5 or so well placed head shots, he will move towards the ladder. After he goes to the ladder, you can move closer to that area. It takes only 2-3 Head shots with the L.Hawk though. Don't get too close to the ladder though, it seems to affect the spawn once you are too close. With about 2 or so head shots, he will leave the fight completely at that point. If you are alone, you have to be careful with this part though, Crimson Heads will constantly spawn.

Once you have all this taken care of, go back to the starting area of this section. There is an infinite ammo box there. Just wait for the zombies to come around the train in a straight line at you. The Riot Gun will kill any normal or Crimson Head in one shot, if you place the shot right.

Killing off your NPC players gives you more kills. Just take Bertha, killing her and reviving her, gives the First Aid Spray back. If she is in a healing mood, she will heal you. Then just take her out of the fight, and revive when needed once again. The NPCs can be idiots, as most gamers should know by now. She may not heal you all the time.

At some points, zombies will get stuck at their spawn, having Leon out of the fight helps. If you walk out, they'll notice you, and come the right direction again. Then you can simply go back between the trains, and continue business as normal. Once the spawn slows down to about 4 to 5 zombies, you can move closer to their spawn. There is a second infinite ammo box beside it. You can simply use the Riot Gun to shoot them as they spawn, for faster grinding.

If you want multiple players, it will obviously take away from your own exp, but you have a safety net if you can't get through professional mode on your own. To go about this, A Lupo and Four Eyes team can be fantastic in this situation. If Four Eyes has a Riot Gun, and her Pheromones. The Pheromones gives you enough time to take Leon out of the fight, without worrying about back attacks. It also gives you time to gather the zombies in a certain area, to pick up ammo, grenades, and herbs.

At the end of this fight, you can easily amass 20k+ exp. That is if you wait till the spawn dies all the way out. With a partner, we hit 19k and 16k, with a kill total of about 1000+ between us. This was all done all professional, for the most exp gain. Finish out the level by Defending Leon to see your hard work in number form. Defending is much easier than killing on professional mode. Just go for Instant Melee kills.

Sorry for the long post, there are other places to boost. Such as Gone Rogue in the Parasite area, and more. I just think End Of The Line works best. As for the amount of exp, you do get a bonus depending on how well your ranking is. I usually end up with 3 S ranks, and a D if I collect 0 collectibles. If you collect at least 8, you will get even more exp. This is of course my preference, other players may have different methods.

This achievement requires a grand total of 252,250xp. One way to save yourself some time would be to pick your prefered xp boosting method, purchasing as few abilities and weapons as possible. Once you reach your total, you go to the character select screen and just upgrade all abilities for a character and then select the next one and do the same and so on. MAKE SURE YOU DON'T START OR BACK OUT OF THE MATCH! As soon as the achievement pops - guide button or disc tray to the dasboard.

When you start the game again you will still have all your xp. The same method can be used for purchasing all the weapons which cost around 210,00xp. Once you have both those cheevos you can spend your xp however you see fit to get any remaining achievements.

Here is a good Video i found on Youtube.