tiling slightly uneven concrete floor

Hi every one i am new and renovating kitchen and games,i have double brick 4 bedroom house.
my question is that the game room floor is not perfectly flat.It's smooth but in one area it's like rough and you can scrape cement dust of of it.
sorry it's the only way to explain it.
i want to tile it but not a 100% sure wether the tiles would eventaully lift in that area.
the games was built onto the house before we bought it about 8 years ago.

So far i have replastered cieling,ripped slidding door out and built frame with french door and put in.
In process of making benches for kithen.

Hi
Either go and hire a concrete grinder and grind it flat, or put some self leveling compound on top of the floor to even it out.
You may have to also seal it by the sounds of it.

Al :)

It's a 6 metre by 7 metre games room overall hieght variation would be 0 to 12 mm. a concrete grinder would be sufficient.
what sort of levelling compound and would it stick/seal to the floor properly.

You should acid wash it b4 tiling too. 6:1 water:pool acid. The bigger the tiles, the flatter the floor has to be. gentle undulations you can get away with if you are using a 330mm or smaller tile. If you have localized depressions you can do what I do and screed them off with cement-based flexible tile adhesive (I use Mapei Keraflex) the day b4 or self levelling cpd. If it's still dusty after the acid wash you'll have to seal it with a primer - ask the tile shop.

CHeers
Michael

Only 330 mm tiles thankfully.
Thankyou for all of your advise i take both of your advises.
first time renovator, i am a mechanical who is now a stay home dad so wife can work.I am enjoying the renovating but it seems challenging some times. The advise given by evevry one is excellent hope to return favour when know abit more.
The only thing i will not touch is 240 volts as i found out the hard way while changing fuse with a towel rapped around me.