What would you need to install upgrade on a pc to play games?

Now i'm just curious want kind of things I would need to buy and install to play PC games smoothly. When I try playing games like mine craft and such I get serious lagg and its not even worth playing ( and that's not the only game I want to play its an example ) but yeah its not just minecraft either pretty much all games. Also I not asking for anything specific just generally what would you look to fix hardware wise ( CPU, motherboard, graphics card) ? And what of thoughts thing would I need to look into statistic wise?

From what I've heard Minecraft is quite a huge game and relies on a huge amount of memory…
More RAM, a 1TB Hard Drive (Caviar Black), definitely an Nvidia graphics card at least 1GB, 2GB would be better, you could also opt for a new CPU 3.0 Ghtz, those items would get you playing pretty much anything.

If you lag while playing Minecraft, your first problem is your CPU, and after your graphic card.
Assuming that with an i3 you could play Minecraft decently, I think you pc is rather old.

Your motherboard would be to change to get a better CPU and graphic card, but then you'll need more cooling and air flow. So, you will need a new case.

1. CPU
2. GPU
3. RAM

the cheapest thing might be get a motherboard with a APU

Buy a good graphic card