I know this method may have been exhausted already, but some people are not aware that it exists.
I just picked up a copy of Nioh for £24.99 after placing a Sainsbury's Groceries order online yesterday to pick up at my local store today with my weekly shop.
You have to spend at least £60 to use the promo code. Nioh is currently priced at £42.99 on their website, so you just need to add a minimum of £17.01 worth of groceries to your basket that you are planning to buy anyway. You can then enter the promo code at checkout to reduce your basket down by £18...effectively making Nioh £24.99.
Promo Code = SCSEAXEFEB
Expires = 16/02/2017
Collection = FREE
Delivery = As little as a £1
New Accounts Only
Hope this helps!