I immediately thought of Welltris: https://www.google.com/search?um=1&hl=en&biw=1920&bih=953&tbm=isch&sa=1&q=blockout&oq=blockout&gs_l=img.3...0.0.0.3672.0.0.0.

I immediately thought of Welltris: https://www.google.com/search?um=1&hl=en&biw=1920&bih=953&tbm=isch&sa=1&q=blockout&oq=blockout&gs_l=img.3...0.0.0.3672.0.0.0.0.0.0.0.0..0.0...0.0...1c..6.img.rR7hL6R1Vao#um=1&hl=en&safe=off&tbm=isch&sa=1&q=welltris&oq=welltris&gs_l=img.3..0j0i24l6.24534.26173.0.26595.8.8.0.0.0.0.179.734.6j2.8.0...0.0...1c.1.6.img.MdSBBwzo3Kk&bav=on.2,or.r_cp.r_qf.&bvm=bv.43828540,d.bGE&fp=ec8fca4e9cb74de&biw=1920&bih=1085 https://www.google.com/search?um=1&hl=en&biw=1920&#3...