Hey everyone, 

Well, I'm hoping to get an MS points card soon (probably 4000 points) and I was wondering what was worth it on the Arcade Marketplace. 
 
Everything I have right now:
Castle Crashers
Braid
Ikaruga
Rocket Riot
The Dishwasher: Dead Samurai
Metal Slug 3
Contra (big mistake that one)
 
And I think that's it, I was thinking Shadow Complex is worth it since I've heard a lot of good stuff but I'm not sure.
 
So, your ideas and opinions?
 
Thanks in advance.
 

Shadow Complex is absolutely worth it.
'Splosion Man is pretty good, if you like puzzle-platformers
Geometry Wars: Retro Evolved 2 is really good
Pac-Man Championship Edition is a ton of fun

Unless you like frustrating games I would say Shadow Complex. 

Thanks for the replies everyone.
I see everyone loves Shadow Complex so that's a definite and I tried Splosion Man at a friend's house and it just seems like it would be a lot more fun playing with other people sitting in the same room as you, so I'll probably get that too.

If you don't own it on another platform, Castlevania: Symphony of the Night.

Shadow Complex
Trials HD
'Splosion Man

" If you don't own it on another platform, Castlevania: Symphony of the Night. "

Ditto on Puzzle Quest: Challenge of the Warlords.   But it's not pretty good, it's fantastic! 
 
Another overlooked gem in the puzzle genre: Poker Smash. 

Braid 
Shadow Complex
Geometry Wars 2
Castle Crashers 
and
I Heart Shift

shadow complex is worth it.

 I made a game with zombies in it is a really good "Indie" game thats only cost $1 and allows up to 4 players to play through local play.  The trial gives you enough to judge give it a download 31M0 and everyone else. 

Get Puzzle Quest.  Right now it's only 400 points.

Other than what you have, Shadow Complex, Castlevania SOTN, and Marvel Vs capcom 2

Shadow Complex

 Pac-Man Championship Edition is well worth the buy.

No XBLA collection is complete without Geometry Wars. If you're into fighters, Samurai Shodown 2, Garou: Mark of the Wolves and Super Turbo HD Remix are all great buys as well.

Monkey Island Premium theme... you're welcome.

MI, shadow complex, 'splosion man to name of few.

TMNT 1989 is a blast online.

Geometry Wars, in any form, will probably eat your soul if you give it the chance.  
 
Bionic Commando: Rearmed is excellent. As is Marvel vs Capcom 2.  
 
I feel your pain on the Contra front. I happened to win that a few years back through a contest Xbox.com was having. Not even worthy of having for free. 

" N+ and Geo Wars 2 of course. "

Dude Shadow Complex rocks the house!

Battlefield 1943 and Shadow Complex

My top 5:
 
Braid
Shadow Complex
Battlefield 1943
Geometry Wars 2
Trials HD

Bionic Commando Rearmed. The music in that game alone makes it worth a purchase! 
Not to say the game isn't good either, its awesome :)

" Battlefield 1943 and Shadow Complex "

Lot's of shit, just depends on what you like.

" Shadow Complex is absolutely worth it. 'Splosion Man is pretty good, if you like puzzle-platformers Geometry Wars: Retro Evolved 2 is really good Pac-Man Championship Edition is a ton of fun "

Both the Banjos are still pretty fun in my opinion.

Don't get 'Splosion Man. It's a boring game.

" Shadow complex, 'Splosion Man, and Trials HD. "

this is my personal preference and its way old and you lot are gonna say its overpriced but bankshot billiards 2 is a lot of fun, but if you don't like pool ignore that
 
but alien hominid is a great buy if you liked castle crashers, and N+ is highly recommend too, so much fun but fustrating as hell

" Shadow Complex Trials HD 'Splosion Man "

I think Shadow Complex is overrated. It's still good though. But I think the games You need most are Geometry Wars: Retro Evolved and Puzzle Quest: Challange of the Warlords. My second choices being Battlefield 1943 and Street Fighter II HD Remix, with Splosion Manand Mega Man 9 coming in 3rd place.