Which site?
Nice site to learn or improve tactics.
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Silly me - post updated now 
I was reading a review of a computer game the other day. They said it 'was like chess but with tactics'
I'm lost for words...
I strongly believe that Richard Teichmann was right in saying that “chess is 99% tactics” – at least, this is 100% sure at “our” level. If I look at my recent games, all of them are won or lost because of a tactics.
While looking for something to improve tactics in a structured way, I stumbled across this site
It looks very well done to me: it is structured in 235 chapters, each of them focused on a particular theme, and it tries to give sound explanations in English (not just sequence of moves) of how to create the seeds of tactical destruction (as Dan Heisman call them) and how to frame tactics into a thought process.
Give it a try, you may like it!