Last Human

Earth is dead and frozen solid, and you're one of the last people off the surface, headed for the starship Aurora when two Nekos tumble out of an experimental wormhole and land in your life. It plays it straight rather than winking at the camera: this is pitched as "Star Trek for adults," story first, sex second.

Your father built the base and got you this far; the ship is the next step, and your first job aboard it is escorting the two Nekos home to Pantheria. Arrival doesn't go smoothly. You end up facing down another Neko who is both familiar and a serious problem.

There's nothing to steer here. It's a kinetic novel, so you read through the episodes as the crew grows into something like a family, and eventually a harem, aboard the Aurora, with comedy and drama doing as much work as the romance. The game is built in episodes and the author says flatly that the current one isn't the end of the story.