I'm partial to the odd Breakout clone every now and again, but to be honest if someone makes a really good one there's not much else to do with the basic concept. Thus Batty on the Spectrum sits in my top 100 pretty much unchallenged.
Shatter isn't a threat to that game, because it takes the 'bat and ball' framework and twists it in all kinds of ways, resulting in a quite unique experience. Vertical, horizontal and circular levels - the latter restricting the player to a lower-third section, end-of-stage bosses that require quite a bit of precise and strategic play, and a push/pull mechanic that allows the player to draw in energy from the remains of destroyed blocks or influence the flightpath of their projectiles. Blocks don't simply sit waiting to be taken out either, and once hit entire sections of the formations will fall towards the player, forcing judicious use of every trick at their disposal and making things frequently quite overwhelming.
Thanks to all these extra features Shatter sometimes feels more like a hybrid of shooter and puzzle game. You have to think about much more than simply losing your 'ball', and the busier levels and especially the bosses become a tense back-and-forth of pushing/pulling, dodging, shielding and occasionally unleashing your collected energy in a barrage of destruction. Lives can fall away quickly during particularly chaotic moments - especially if you're enough of a gambler to fire out two or three projectiles at a time (each counting as a life).
Shatter plays wonderfully and is very addictive, but the icing on the cake is the soundtrack. Videogame electronica at its very, very best. In fact the soundtrack is without question my favourite album of this year and is probably responsible for a good 50% of my enjoyment in playing the game. That's not a strike against the gameplay though, as anyone who knows me knows how much importance I place on the music of videogames.