If you want to pick up a quick 460 points in about 2 to 3 hours, then History Channel Battle for Pacific is a game where you can easily pick them up without too much effort. The rest of the points lie in multi-player, but they can be achieved on Player matches by boosting with a friend (except for one). These can be time consuming. You could try doing them legit, but there is hardly anyone online.
You will have to play the single player campaign on Hard difficulty, but don't worry. The enemies are really, really lame. Even on Hard! You will feel like you are playing Recruit (Easy) on Call of Duty. The missions are also very short, so you could complete the whole campaign in one lazy afternoon. You will need to because this game is slightly bugged on completing the game on Hard. That is you have to complete it in ONE sitting. See the achievement guide below.
That said, there are also some tiny annoying game-play aspects. You have to follow some dude almost throughout the entire campaign and if you don't, mission failed. You will be sick of hearing "Don't get lost, follow me!" which he continually repeats. He barely gives you enough time to pick up an enemy weapon. There are also some script bugs where the dude, you are supposed to be following, just stands there. Reloading a checkpoint normally fixes this.
ACHIEVEMENT GUIDE
Complete Wake Island - 10 points
Beat Wake Island on any difficulty setting.
Ok, forget about doing this on Easy or Normal. Start the game on Hard. That way you will pick up all the level completion points and "Valor" (Hard) points in one play through as they are all stackable. Hard isn't hard at all. I died once throughout the entire campaign and that was because I stepped on a mine I thought I had diffused.
There are also reports of a bug. (There was an update for this game, but I am not too sure if it fixed this) If you are playing this on Hard, you need to complete the entire campaign in one sitting or "Five Star General" achievement (beat the game on Hard) will not unlock. You can not turn off your Xbox or reload a game later. So make sure you have the time to do this campaign in it's entirety. It should only take 2 to 3 hours anyway.
Complete Bataan - 10 points
Beat Bataan on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Guadalcanal 1 - 10 points
Beat Guadalcanal 1 on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Guadalcanal 2 - 10 points
Beat Guadalcanal 2 on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Leyte 1 - 20 points
Beat Leyte 1 on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Leyte 2 - 20 points
Beat Leyte 2 on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Luzon - 20 points
Beat Luzon on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Iwo Jima 1 - 20 points
Beat Iwo Jima 1 on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Iwo Jima 2 - 20 points
Beat Iwo Jima 2 on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Iwo Jima 3 - 20 points
Beat Iwo Jima 3 on any difficulty setting.
See "Complete Wake Island" achievement above.
Complete Wake Island With Valor - 20 points
Beat Wake Island on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Bataan With Valor - 20 points
Beat Bataan on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Guadalcanal 1 w / Valor - 20 points
Beat Guadalcanal 1 on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Guadalcanal 2 w / Valor - 20 points
Beat Guadalcanal 2 on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Leyte 1 With Valor - 20 points
Beat Leyte 1 on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Leyte 2 With Valor - 20 points
Beat Leyte 2 on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Luzon With Valor - 20 points
Beat Luzo on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Iwo Jima 1 With Valor - 20 points
Beat Iwo Jima 1 on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Iwo Jima 2 With Valor - 20 points
Beat Iwo Jima 2 on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Complete Iwo Jima 3 With Valor - 20 points
Beat Iwo Jima 3 on the Hard difficulty setting.
See "Complete Wake Island" achievement above.
Five Star General - 100 points
Beat the game on the Hard difficulty setting.
This achievement is glitched. You have to complete it one sitting. See "Complete Wake Island" achievement above.
MULTIPLAYER ACHIEVEMENTS
Japanese Weapon Expert - 50 points
Accumulate 500 kills with any Japanese weapons in any multiplayer mode.
All the multiplayer achievements (except "to The Victor Go The Spoils") can be achieved in Player matches and only require two people to start. So you could easily boost with a friend. There are over 500 points to be had by doing this, so it might be an investment to rent two copies. You could try doing these legit, but I actually NEVER found anyone online.
Most of the multiplayer achievements are self-explanatory and the games are all standard multiplayer modes.
American Weapon Expert - 50 points
Accumulate 500 kills with any American weapons in any multiplayer mode.
See "Japanese Weapon Expert" above.
Marksman - 20 points
Get 200 headshots without a scope or pistol in any multiplayer mode.
See "Japanese Weapon Expert" above.
Sniper - 20 points
Get 100 headshots using a scope in any multiplayer mode.
See "Japanese Weapon Expert" above.
Light Gunner - 20 points
Accumulate 100 kills with the Thompson or Type 100 in any multiplayer mode.
See "Japanese Weapon Expert" above.
On The Front Lines - 20 points
Host and complete 100 mutiplayer matches.
See "Japanese Weapon Expert" above.
Heavy Gunner - 20 points
Accumulate 100 kills with the BAR or Type 96 LMG in any multiplayer mode.
See "Japanese Weapon Expert" above.
Defensive Front - 20 points
Kill the flag carrier 5 times in a CTF game.
See "Japanese Weapon Expert" above.
Leadership - 20 points
Win 50 Team Deathmatch, 50 Capture the Flag or 50 Team Elimination games.
See "Japanese Weapon Expert" above.
Total War - 20 points
Have a 5 to 1 or better Kill to Death ratio in a multiplayer match (minimum of 20 kills).
See "Japanese Weapon Expert" above.
Grenadier - 20 points
Accumulate 50 kills with Grenades in any multiplayer mode.
See "Japanese Weapon Expert" above.
Close Combat - 20 points
Kill 50 opponents with melee attacks in any multiplayer mode.
See "Japanese Weapon Expert" above.
Going Out With A Bang - 20 points
Kill yourself and a opponent with an explosive 10 times in any multiplayer mode.
See "Japanese Weapon Expert" above.
To The Victor Go The Spoils - 20 points
Be the most skilful player in a Ranked Match.
You need to be first place in a ranked match. Ranked matches require four players to start.
Dueler - 20 points
Accumulate 50 kills with a pistol in any multiplayer mode.
See "Japanese Weapon Expert" above.
Elite Warrior - 20 points
Kill everyone on the opposite team in a Team Elimination game.
See "Japanese Weapon Expert" above.
One-Man Army - 20 points
Be the only person on your team to score points in Capture The Flag game.
See "Japanese Weapon Expert" above.
Last Man Standing - 20 points
Win 10 Elimination games.
See "Japanese Weapon Expert" above.
Ground Support - 20 points
Carry the flag 5 times in a Capture the Flag game.
See "Japanese Weapon Expert" above.
Not Home By Christmas - 20 points
Win a Deathmatch or Team Deathmatch game with a 50 kill limit.
See "Japanese Weapon Expert" above.
Trench Gunner - 40 points
Accumulate 50 kills with the Trench Gun in any multiplayer mode.
See "Japanese Weapon Expert" above.
The Promotion Is Yours - 30 points
Win a Deathmatch game by 10 points.
See "Japanese Weapon Expert" above.
Complete Wake Island - 10 points
Beat Wake Island on any difficulty setting.
Complete Bataan - 10 points
Beat Bataan on any difficulty setting.
Complete Guadalcanal 1 - 10 points
Beat Guadalcanal 1 on any difficulty setting.
Complete Guadalcanal 2 - 10 points
Beat Guadalcanal 2 on any difficulty setting.
Complete Leyte 1 - 20 points
Beat Leyte 1 on any difficulty setting.
Complete Leyte 2 - 20 points
Beat Leyte 2 on any difficulty setting.
Complete Luzon - 20 points
Beat Luzon on any difficulty setting.
Complete Iwo Jima 1 - 20 points
Beat Iwo Jima 1 on any difficulty setting.
Complete Iwo Jima 2 - 20 points
Beat Iwo Jima 2 on any difficulty setting.
Complete Iwo Jima 3 - 20 points
Beat Iwo Jima 3 on any difficulty setting.
Complete Wake Island With Valor - 20 points
Beat Wake Island on the Hard difficulty setting.
Complete Bataan With Valor - 20 points
Beat Bataan on the Hard difficulty setting.
Complete Guadalcanal 1 w / Valor - 20 points
Beat Guadalcanal 1 on the Hard difficulty setting.
Complete Guadalcanal 2 w / Valor - 20 points
Beat Guadalcanal 2 on the Hard difficulty setting.
Complete Leyte 1 With Valor - 20 points
Beat Leyte 1 on the Hard difficulty setting.
Complete Leyte 2 With Valor - 20 points
Beat Leyte 2 on the Hard difficulty setting.
Complete Luzon With Valor - 20 points
Beat Luzo on the Hard difficulty setting.
Complete Iwo Jima 1 With Valor - 20 points
Beat Iwo Jima 1 on the Hard difficulty setting.
Complete Iwo Jima 2 With Valor - 20 points
Beat Iwo Jima 2 on the Hard difficulty setting.
Complete Iwo Jima 3 With Valor - 20 points
Beat Iwo Jima 3 on the Hard difficulty setting.
Five Star General - 100 points
Beat the game on the Hard difficulty setting.
Japanese Weapon Expert - 50 points
Accumulate 500 kills with any Japanese weapons in any multiplayer mode.
American Weapon Expert - 50 points
Accumulate 500 kills with any American weapons in any multiplayer mode.
Marksman - 20 points
Get 200 headshots without a scope or pistol in any multiplayer mode.
Sniper - 20 points
Get 100 headshots using a scope in any multiplayer mode.
Light Gunner - 20 points
Accumulate 100 kills with the Thompson or Type 100 in any multiplayer mode.
On The Front Lines - 20 points
Host and complete 100 mutiplayer matches.
Heavy Gunner - 20 points
Accumulate 100 kills with the BAR or Type 96 LMG in any multiplayer mode.
Defensive Front - 20 points
Kill the flag carrier 5 times in a CTF game.
Leadership - 20 points
Win 50 Team Deathmatch, 50 Capture the Flag or 50 Team Elimination games.
Total War - 20 points
Have a 5 to 1 or better Kill to Death ratio in a multiplayer match (minimum of 20 kills).
Grenadier - 20 points
Accumulate 50 kills with Grenades in any multiplayer mode.
Close Combat - 20 points
Kill 50 opponents with melee attacks in any multiplayer mode.
Going Out With A Bang - 20 points
Kill yourself and a opponent with an explosive 10 times in any multiplayer mode.
To The Victor Go The Spoils - 20 points
Be the most skilful player in a Ranked Match.
Dueler - 20 points
Accumulate 50 kills with a pistol in any multiplayer mode.
Elite Warrior - 20 points
Kill everyone on the opposite team in a Team Elimination game.
One-Man Army - 20 points
Be the only person on your team to score points in Capture The Flag game.
Last Man Standing - 20 points
Win 10 Elimination games.
Ground Support - 20 points
Carry the flag 5 times in a Capture the Flag game.
Not Home By Christmas - 20 points
Win a Deathmatch or Team Deathmatch game with a 50 kill limit.
Trench Gunner - 40 points
Accumulate 50 kills with the Trench Gun in any multiplayer mode.
The Promotion Is Yours - 30 points
Win a Deathmatch game by 10 points.
5-10 Hours 