I am actually building the same game! Great to hear somebody else also want to build a building game like this. Keep in mind copyright gives you a lot of restrictions. It makes it almost impossible to create this game.
@dollychun already shared it, but if you are curious about what possiblities you have. Check out my post. It will answer a lot.
Well, a story between Roblox and Lego happened.
Roblox was just in it’s early days, and it looks like a Lego game.
Lego knew about this, asked Roblox to change it so Roblox changed it to square studs.
If you notice, in the old website there is a notice saying "We are not inafilitrated with Lego and trademarks.
For the original poster:
This isn’t a good idea, you could get a DMCA copyright and the game could be taken down. Just don’t make it too similar to the real lego.
That sounds like it would be a neat game. Maybe you could find some way to make them stick together with a sticky substance or something, and call the game and/or the blocks, Bloxy Building, or something. Just some ideas.