Two of the best turn-based strategy games involving squad and resource management, X-COM: UFO Defense
and Terror from the Deep
downloads have been patched to run without problems on any modern rig.
Shoot down enemy UFOs, trap your enemies and salvage their technology to improve your own. Night missions tend to be extremely suspenseful, especially when your team is whittled down to it's last few members in an area packed with aliens.
Many sleepless nights were blamed on this series. The first episode requires a little configuration since it's map scroll speed is set to maximum.
Name: X-COM: Terror from the Deep