This is my block game I’m making to learn OpenGL and efficient rendering techniques, this is my current progress after a week and a half:
Looks nice, using VBOs or still in immediate mode? 
He said efficient rendering techniques so no, not immediate mode.
Nice. What techniques are you using?
He said he wants to learn them so maybe he currently uses immediate mode and now tries to improve and change it to display lists and VBOs? 
I did try this in immediate mode, but it was slower than it is now, so I switched to VBOs. I’m currently working out a solution to generate the terrain in chunks, similar to minecraft, it’s kind of slow at the moment, not very efficient at all 
How are you handling your chunks?
What kind of data do they actually hold?
How many of them are there in your game?
Is there dynamic chunk-loading?
Tell us about your game, then we might be able to help you.
Have a nice day!
- Longor1996