Obviously having OpenTTD available for free on Steam would jeopardize Atari's paid rerelease of Transport Tycoon Deluxe, so I think this is a good compromise. Hopefully they rigged it up so the assets from Transport Tycoon Deluxe get picked up automatically by OpenTTD when you install the bundle. I also hope that Atari will be sharing some of the revenue from the bundle with the OpenTTD team as part of this arrangement. They've spent the last 20+ years adding nice quality of life features and keeping the game playable, and I think they deserve to be rewarded for that effort. Going back to stock TTD after playing OpenTTD feels like a massive downgrade, like going from vim to BSD vi.