Freespace 2 is one of the best space flight games out there. With a choice of ships and weapons that gets larger as you go through the game and you can customize the ships of your squad mates as well, if you have the time or you want to. By the end of the game you will probably want the next game in the series but at the moment it seems that this may be the last good space flight sim for a while. Obviously the graphics are going to be a bit out dated by they aren't too bad. Probably a good idea for you to buy this unless you don't really like space/flight sims.
Shattered steel is a good game but it is old and diffidently showing it. Despite this it has decent gameplay, though the hit detection could be better. The mission briefing is similar to the one in Evolva though it doesn't really tell you what your exactly supposed to do though you generally get the out line (i.e. kill the red things/ the things shooting at you). One mission gets you defending an area larger then your radar can see while it gets attacked from all directions by a multitude of enemies, kind of hard since 2/3rds of the enemies aren’t in viewing distance and there is probably another fifth not seeable by your radar. Apart from that many of the missions are fairly easy.
