So this game has one single achievement, and it seems like nobody has ever gotten it... yet. I've beaten the game, once with the Dog ending, once with the Wasp ending, and then the Dog ending once again on 2x mode. I'm not sure if this achievement is actually obtainable or not, anyone got any ideas? Also, are there any endings other than the main two that anybody has discovered?...

It's impossible. I'm not kidding, the Gadot project of a game does not call the Steam library, so there is no line of code that can give you the achievement. This means that anyone who has it is a cheater. Also, it seems almost impossible to complete the second hidden level. Theoretically it is possible, I checked the collisions of the two boxes and they match (although the collision of the second box is different from its sprite). But in practice it is almost impossible to complete the level. I started...

Если вы знаете как получить достижение в этой игре, расскажите пожалуйста, буду очень благодарен!

Instead of the game, it launches the app Spacewar. And how to get the achievement?

Секретный уровень проходим? Только честно.