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For anyone curious: all Steam keys, only 1 of each of the three deeply discounted titles can be purchased per account there (i.e. no buying 5 Arkham Asylum keys in one go to plop on the grey market or peddle through trading, etc). The Arkham and LEGO Batman title are currently part of the free (and DRM-free, at that) offering through Epic Games Store. Of course, you'd need to register an account to claim the game and then download them via the launcher so it depends on what you hate more.