[spapas82]

Are you sure that you can use "Lego"? Isn't that word a trademark or something? "Building blocks" should suffice to convey the meaning without any legal problems.

[pennomi]

I think if you were to comply with all the branding guidelines, you would need to say something along the lines of“Blocks are like LEGO™ bricks…”.

Since there’s little chance of the product getting confused with official LEGO products, you’re probably okay… though IANAL.

[NikkiA]

Eh, I clicked on it wondering what kind of physical lego-compatible bricks they were offering, so I'm not so sure.