In which case, you'll definitely want to read through the links that THEBERBSTER has above in his post. He helps walk you through the process. SH3 is easiest to deal with from Steam, followed by SH4. SH5, you have to do some hoop jumping, but you barely get off the floor for it. One thing to note with SH4 from Steam is that you ~have~ to purchase the UBoat Missions separately. What you get when you buy SH4 from them is v1.3, and you cannot apply a v1.4 update to it (Steam security). Most mods are made for v1.5, UBoat Missions... As for "King" of the series, going by the mods, SHIII is... it's a gorilla.