Steins;Gate, Seikaisuru Kado Recommendations
Both are sci-fi. Stein's Gate involves a mad scientist developing time travelling, whereas Kado involves an Alien, higher dimensions and mind boggling devises. In both anime character development plays an important role, so even though they are quite different they do have a similar feel.
Both Steins;Gate and Seikaisuru Kado start off by a mysterious phenomen. First episode leaves many questions and you need to keep watching to understand what the F have you just witnessed.
Both shows are sci-fi, S;G is primarily focused on time traveling whereas Seikaisuru Kado is about an alien arrival. Even though plots differ, shows have similar atmosphere and some traits in common - such as drama, plot twists, dialogues and commentary on science and politics, philosophical questions, serious and realistic worlds. Both shows involve a potentional war over technologies.