Getting a 360 soon, have one question.

That's a difficult question, as some of those games are in different genres, and thus don't compare well. The Orange Box is impressive both in the volume and diversity of its content. Oblivion will keep you busy for a very, very long time. Mass Effect is a shorter RPG than Oblivion, but what's there is much more emotionally involving.

My personal favorite out of those is Mass Effect, but it will only take you around 12 hours or so to beat. If you get Oblvion (which is also a favorite of mine) it could literally last you hundreds of hours, depending on whether you like it or not of course. So it sounds like Oblivion is best for you.TheRealMC01

It will take the amount of time that the person in the response said in the quoted message above if you rush though games or that person only played it for 12 hours of gameplay and then give up for whatever reason. Otherwise it will take an average gamer about 40-60 hours of gameplay. It took me 74 hours of gameplay in my first playthrough as I like to explore and take my time at the Citadel.

If you would like to read a mostly(99%) spoiler-free review of Mass Effect then read my review this is my first review of a videogame which is here: http://www.gamespot.com/xbox360/rpg/masseffect/player_review.html?id=562231

As for the other games that you listed in the poll I voted for Mass Effect which is my #1 favorite Xbox360 game so I would say get that, but The Elder Scrolls IV: Oblivion and The Orange Box(Half-Life games) are also two of the greatest games ever which are my #2 and #3 favorite Xbox360 games.

The Elder Scrolls IV: Oblivion could take 100's of gameplay hours, as for me I have it on the Xbox360 and the PS3. On the Xbox360 I have so far only 39 hours of gameplay and that is doing a few of the side quests and most of the Knights of the Nine quests and some of the main quests, and on the PS3 I have just over 80 hours of gameplay and all I have done is are some side quests. There are like 200 different side quests alone not included the main quests of the Knights of the Nine or the Shivering Isles in this great game.

The Orange Box(Half-Life games) could take about 20 hours of gameplay for just Half-Life 2 and Episode 1 could take about 8 hours of gameplay and Episode 2 could take about 5 hours of gameplay. For me I have played Half-Life atleast 4 times on the PC and the Xbox360 combined with times different times between 22-34 hours of gameplay, and Episode I have only played on the Xbox360 and I am about halfway through and I have 6 hours of gameplay. The Orange Box is that great of a game that I got it for the PS3 a couple of weeks ago brand-new/sealed for only $19 with shipping off of eBay and so I can't wait to playthrough Half-Life 2 again and then play Episode 1 and 2.

I say...Mass Effect. Its an exclusive game, it has downloadable content. The story is great, and it has nice replay value. Its the best RPG game I have ever played.

Only bad thing about it, It doesnt have any multiplayer. When you first get your 360 the best thing to do MIGHT be to get a game with great multiplayer so that you can see how good XBL is. Other than that, its Mass Effect. I cant wait until the next one.