This is a grey area. Technically, downloading an IPA for a game that is still commercially available (Subway Surfers is free on the App Store) is copyright infringement.

The initial IPA for iOS 4.3 or higher had a file size of approximately 27 MB.

By version 1.9 (New York World Tour), the game exploded. By 2.0, hoverboards and keys made it more casual-friendly. But version 1.0 remains the "pure" version—the one where your high score was just a number, not a ticket to a season pass.