While not trying to blow my own horn here, but if your nephew likes WW1 you might have a look at Canvas Knights WW1 game, its easy to play, stand alone game and current as its still being worked on and things are being made for it, there are add-on's of planes, ground vehicles, skins, off line missions and it has a online MP, here is the minimum requirements;
Minimum Requirements to run Canvas Knights game.
CPU: Intel Pentium 4 2.0 GHz, Intel Core 2.0 GHz, AMD Athlon 2000 or better
RAM: 1GB or better
Video Card: NVIDIA GeForce 6800 GT, ATI Radeon 9800 Pro or better
VRAM: 128MB of Graphics Memory or better
Sound Card: DirectX 9.0c or DX10 Compatible
OS: Microsoft Windows XP or Vista or Windows 7
DirectX: DX9.0c or DX10
There is a thread here at SimHQ on it;
http://simhq.com/forum/ubbthreads.php/topics/3948513/Canvas_Knights_WW1_Game#Post3948513And here is the forum where it all happens;
http://allaircraftsimulations.com/forum/viewforum.php?f=112And its all free ;-)
Deutschmark