Fallout 3 is barely played these days, it's the least popular 3D Fallout (on Steam it's 24 hours peak is barely 1600 players vs 18 000 for NV, 22 000 for 76 and over 50 000 for 4; on consoles it's probably even more skewed in 4's direction), so I think that's why it's doing better than 4...