I have to agree with @Shadowblind. Halo 1 was released in 2002 and at the time there was nothing quite like it. You felt the enemy had personality especially when you threw a sticky grenade at them :) Halo also introduced more of a us against the aliens feel, like an epic battle, or struggle for life. When it was released on the PC in 2004, it wasn't the same mainly due to FPS moving forward since then. PC gaming was all about FPS and still is in some way, people would upgrade just to play the latest ones.
As for the Conduit, people like value for money. A multiplayer component like with Killzone 2 or other help to establish game sales. Also what people seem as good for the Wii, others feel they have seen it all before, especially if you own a PC, PS3 or X360. I thought the game was alittle generic, but I did like the generators for the monsters idea. People who are technologically minded always like the latest thing and in the case of FPS, its' Killzone 2, Halo 3, Far Cry 2... etc.. etc..
But all things aside the game shows off some of the best graphics for a Wii. It does deserve good sales, but I don't think it will reach them. The more adult Wii owners will probably pirate it, and as for the others, well some will buy it. I see the game as more of a rental. Time will tell.