I normally go for fighting or dungeon or puzzle games but i want to get my teeth stuck into something that will keep me going for a long time.
In the satisfactory game how do you choose what to build , does it go on the lines of you can build anything as long as you have the right materials.
Does is have all buildings greyed out in some sort of inventory until you have the things you need to make them
Not 100 percent sure what you mean about building anything with the right materials. You can build whatever you want with the building pieces, but the machines themselves (and there are many of them) are premade, and you can build them once you have them unlocked and have the right materials. The questions you'll have are things like, how many do you need, where do you place them, how fast should you set the machine to work, how do you get the needed materials to the machine, and what do you do with the materials that it makes (which will probably need to go both to storage and to other machines on conveyor belts). There's a lot of strategy to it.
If you are wanting a game where you invent or create machines out of various parts, you could look at something like Scrap Mechanic, which is pretty fun but completely different from Satisfactory. In Scrap Mechanic, you have a bunch of different components, and you see what all you can make out of them. For instance, you can create machines that defend your garden from the nightly robot raids, or you can build cars or try your hand at boats and airplanes.
They are both good games, but have different types of engineering involved. Satisfactory is more logistical, although you can build any type of building you want much, much easier than in Scrap Mechanic. So if you want to make a really cool looking building out of your factory you can do that.