- The fact that the game has a 'pet horse' button.
- Also the fact that your horse is so loyal to you. The relationship between Wander and Agro is one of the only clear-cut things in this game, and it is clear that they had a deep and loving bond.
- Depends on your interpretation of what's going on, but Wander's devotion to Mono is rather heartwarming. He's clearly in love with her (one of the few things you're sure of) and he'll do anything to bring Mono back to life, even kill giant monsters and let a mysterious entity possess his body.
- Agro survives. Bless that wonderful horse...
- When Mono finds baby Wander in the pool. Though this probably isn't the reunion Wander had hoped for, he at least reunited with the love he fought so desperately to bring back to life, and that in itself is beautiful.
- Seeing that deer during the epilogue. Actually, after Dormin's demise, the valley seems much more full of life than during the game, meaning that Mono, Agro and Wander are maybe not completely screwed after all.
Heartwarming / Shadow of the Colossus