Hmm let's see. So the Subnautica games are survival games with a lot of exploring, uncovering mysteries, finding logs, figuring out what happened to you, the alien civilization, the ecosystem, etc.
If you like Obra Dinn, recommended elsewhere in this thread, The Case of the Golden Idol has some similar energy of looking at scenes and solving who's who and what's what and how this person died.
Chants of Sennaar is a game where you decipher fantasy languages and learn about the peoples that speak them while progressing up a tower and solving puzzles.
Viewfinder is a surreal-perspective puzzler with lots of narration and backstory from the characters
Sable is an exploration game with puzzles to solve, in a fancifuil sci-fi desert world with towns and NPCs and crashed spaceships to explore
The old Escape Velocity trilogy (though nowadays you'll need a classic Mac emulator to play them) are top-down ship captain games where you fly your ship around, trade, fight, do missions, usually have multiple storylines going on at once, lots of planets, ships, stations, factions, etc. The modern game Endless Sky is explicitly molded on the EV series.
Sunless Seas and its sequel Sunless Skies have some similarity to EV mechanically, but with a lovecraftian, steampunk aesthetic to the world, and lots of world-building.
Beyond Good and Evil is a third-person action game that has good plot, characters, and worldbuilding, and there are updated versions available that run on modern hardware.
Bastion is an isometric action game a little like Diablo in the combat mechanics but with no numbers for you to worry about. Explore the aftermath of a most peculiar apocalypse and discover the world that was and the peoples who lived there. Good characters and worldbuilding.
Hmm, thinking about it, I think maybe the direct CO~2~ exhaled during exercise may not be the most useful metric for human-powered travel. Every atom of that carbon was recently removed from the atmosphere by the plants you ate or that went to feed the animals you ate. It isn't carbon that was underground for millions of years as is the case with fossil fuels.
Unfortunately, growing the food does involve carbon emissions from fossil fuels. Taking this page's number of 2.5t/yr for the typical American diet which they assume to be 2,600 kcal/day that works out to 2.6g of CO~2~ / kcal (2.5t / 365 / 2600 = 2.6E-6 t = 2.6g), or 52.7 g / km for cycling, or similar to an electric car if the chart is at all comparable (I don't know the chart's methodology; for example for the fossil fuel transport options does it count the carbon cost of producing and transporting the fuel or just the tailpipe emissions?). Changing one's diet looks like it would improve this; the best-case would be a vegan diet which would result in 31.6 g / km.
Now that's just based on numbers from that one source, so I don't know how reliable they are. It does say it includes the large amount of wasted food in the final number, and I don't know if the numbers in the original chart are that level of conscientious. Regardless I think the takeaway here isn't that cycling is bad, it's that our food production system is terrible and it badly needs to become way less carbon-intensive.