TL:DR; Probabily the most challenging Tetris game ever, because you have to play three at the same time!
In the game of Tetris you control the position of the dropping block so that a complete row is formed, when that happens, the row will be destroyed. This game is challenging because you have to play three tetris games at the same time!
Lode Runner. Episode II: Bungeling Away. Second episode of series by ZX Games. Another set of 75 levels for those who have completed the first episode. Infinite lives, quick save & load, level browser, full-screen & window modes. And level editor.
An unknown aggressive alien race gained control of the Pulsarius system. You, as the fighter pilot, must complete the hardest mission. Head for the colonies and rescue its people from the enslavement of extraterrestrials.
Brick-busting classic arkanoid clone with retro ZX Spectrum graphics, over 30 bonuses, advanced aiming with your pad, cool efects and sounds.