- last post: 01.01.0001 12:00 AM PDT
Definitely get ODST first. Buying ODST sort of gives you 2 games-the ODST campaign and Firefight, and Halo 3's multiplayer. If you already know how Halo 3 ends, ODST will give you a better playing experience, considering that it has a fresh, new campaign. Also, 3 Halo 3 maps will be exclusive to only ODST.
However, I'd only suggest to buy Halo 3 if you have strong emotions to "finish the fight".