I picked up Sons of Liberty, had a small talk with Dan and guys at Gamestop about the differences and which is better, SoL or Substance...they told me "Well ones 5 bucks the others 15 " But pretty much there was no real difference in gameplay, virtually the same, but Substance had more VR missions and funky lil features, but not worth the 15 bucks. So I went ahead and got SoL (I like saying SOL I say it alot at work) for 5 bucks.......they tried to get me to pay 200 for Steel Battalion......I gave them the evil glare of DOOM Zim style and they stopped.....plus they got it in the back room if need be I'll play it in there with them!