Existing Lotto Extra subscribers will probably either be given the chance to switch their sub to Dream Number or to cancel their sub (this is a guess - I don't have confirmation on this). People who play Lotto Extra via a playslip will only be allowed to play up to 8th July of course (i.e. it enters a rundown period in the 8 draws leading up to the final Lotto Extra draw). If the final Lotto Extra jackpot isn't won, it's rolled down to the highest tier that has any winners and is shared amongst them - this may indeed the time to play your first ever Lotto Extra ticket (since the odds of the lower tier are 55,000 to 1 - way better than 14m to 1)!
Dream Number is the first online game run by Camelot where all the 28p of the £1 ticket cost goes to the Olympics Fund and not to generic Good Causes. Unlike Lotto Extra, it is played independently of any other game and involves 7 machines each containing 10 balls numbered 0 to 9 - one number is drawn from each machine to produce a 7-digit number.
The main Lotto playslip will have one random 7-digit number printed on it and hence if you use the playslip, you can only play that number (albeit up to 8 weeks and 2 draws per week - i.e. a maximum of £16 per playslip). Yes, this makes the game more "Random Random Number" than Dream Number - even if you ask the shop to manually play Dream Number, they will get the lottery terminal to simply generate a 7-digit random number. Effectively, the whole game is Lucky Dip-based and you cannot pick your own 7-digit Dream Number. I imagine we might see many discarded playslips on shop floors as people rifle through them trying to find a "good" Dream Number!
If the first digit you pick matches the first machine's digit, you win £2. Yes, this would appear to be the first time the order of a "main ball" actually matters in an online game. The full prize tier is as follows:
Match all 7 in order £500,000 Match first 6 in order £50,000 Match first 5 in order £5,000 Match first 4 in order £500 Match first 3 in order £100 Match first 2 in order £10 Match first 1 in order £2
Note that if you had the number 1234567 on your playslip or via the terminal, then the 7 balls have to be drawn as 1, 2, 3, 4, 5, 6 and 7 in that order for you to win the jackpot. Personally, I think that with odds of 10m to 1 to win, the jackpot should have been £1m - as it stands, it may cannabilise sales from the Thunderball game, There will be a Wednesday and Saturday draw each week that is likely to be televised by the BBC (not clear if they'll do it live on Wednesday or have a static caption like they scandalously do for the Extra).