
The first two games are very different, they're 90s style isometric RPGs. I think they're amazing but they're probably not at all what you're used to. Fallout 3 changed it up to a shooter with RPG elements, and New Vegas and 4 kept that general vibe. 3 and New Vegas show their age but NV has the best story and writing. 4 is probably the most approachable since it's the newest and the gameplay is the most polished, but imo it has the worst writing by far.