I have been looking over UK Consumer Rights and the appropriate bill is here
In it it states that Digital content should be of "satisfactory quality"
"34 (1) Every contract to supply digital content is to be treated as including a term that the quality of the digital content is satisfactory."
"34 (2) The quality of digital content is satisfactory if it meets the standard that a reasonable person would consider satisfactory, taking account of—
(a) any description of the digital content"
I think DF can get around that one, because they never made any flat claims of what DF-9 will do, however it goes onto say:
"34 (3) The quality of digital content includes its state and condition; and the following aspects (among others) are in appropriate cases aspects of the quality of digital content—
(a) fitness for all the purposes for which digital content of that kind is usually supplied;
(b) freedom from minor defects;"
now DF-9 is a game, games are fun if you could argue that the state DF-9 is in on release is not fun, you could potentially get a refund, or retroactive discount on the game.
freedom from minor defects is a bigger one though, because if on release DF say they are not doing anything on the game anymore, and it has bugs, which could be considered "minor defects"
now the bill does not outright give a consumer the right to a refund, however it does say this
"42 (2) If the digital content does not conform to the contract, the consumer’s rights (and the provisions about them and when they are available) are—
(a) the right to repair or replacement (see section 43);
(b) the right to a price reduction (see section 44)."
(a) I do not think applies, because a repair would constitute a patch, which DF won't do, and a replacement implies it is the specific copy of the digital content which is faulty and another, fully working, copy of the same digital content is possible.
but (b) might be possible
"44 (1) The right to a price reduction is the right to require the trader to reduce the price to the consumer by an appropriate amount (including the right to receive a refund for anything already paid above the reduced amount).
(2) The amount of the reduction may, where appropriate, be the full amount of the price.
(3) A consumer who has that right may only exercise it in one of these situations—
(a) because of section 43(3)(a) the consumer can require neither repair nor replacement of the digital content, or
(b) the consumer has required the trader to repair or replace the digital content, but the trader is in breach of the requirement of section 43(2)(a) to do so within a reasonable time and with out significant inconvenience to the consumer."
43(3)(a) is simply
"43 (3) The consumer cannot require the trader to repair or replace the digital content if that remedy (the repair or the replacement)—
(a) is impossible"
and 43(2)(a) is
"43 (2) If the consumer requires the trader to repair or replace the digital content, the trader must—
(a) do so within a reasonable time and without significant inconvenience to the consumer;"
so it is my judgement that if when the game releases at 1.0, and the game has bugs which DF have said they will not fix, you are within your rights to get a retroactive discount on the game under UK law.