Re: Computer game/simulation for tactical training?
What kind of fieldcraft? Are you talking target ID, concealment, movement, etc?
Most of that stuff would best be done with another person, out in real life. If you want to develop some mental skills that will help with whatever you plan on pursuing in terms of "fieldcraft," look up KIMS games and practice drawing. All you need is a camera for the first one, and a piece of paper and a graphite stick for the second.
Also, map and compass and some woods work great for land nav. Start by hiking some well worn trails that are clearly mapped. Bring a GPS and test your map skills to see how accurately you can plot your position, and then check with the GPS. As you get better, work to getting into real wilderness if you are the survivor-type. Me, I have enough fun telling ghost stories around the campfire, so I don't really do much of any of the above unless I'm really bored.