Mars, the First Son of Heaven, is a great new to the Dota 2 hero pool. He is a tanky Strength hero but the can also semi-carry. His skillset shows us his only strategy: jump into battle, even his responses point towards the same thing.
Mars is the name of mythical Roman god of war, but Mars, our hero, looks very much Greek, with his spear and his signature greek shield. The answer to that mistery is this: Mars is the son of Zeus (who in Greek mythology is the god of gods) and he hated him so much that he changed his name (from Ares to Mars, we believe) so he can avoid any association with Zeus.
All in all, he is a very fun hero to play, a strong hero, and doesn't have that many hard counters (except for Viper).
Read everything you need to know about him here https://dota2.gamepedia.com/Mars
Now go and own some people until he gets nerfed!