1.Game Modes: Normal, Hardcore, Solo Self-Found, and Offline Play
The game will feature Normal and Hardcore as its game modes. Hardcore remains the same as seen in previous Diablo installments, meaning that the character will be lost forever upon death. There are no plans for characters being converted to Normal after dying, like in Path of Exile for example.
2.Grouping vs. Solo Play
You will be able to form groups of up to four players. Sticking close together will grant players a buff which grants 5%, 8%, or 11% bonus XP, depending on the number of players nearby. Once a group is formed, the party leader's state of the campaign and world will be used. Players can communicate with each other through the use of in-game party voice chat.
The developers are aiming for solo play to be as rewarding as group play. If that can't be achieved they want to err on the side of group play to avoid that everyone only plays solo. All content progression and items will be available to everyone, regardless of solo or group play.
New to the Diablo universe, mounts help the player traverse the vast regions of Sanctuary. There will be many obtainable horse breeds and other mounts from completing puzzles, finding hidden locations and killing specific monsters, just to name a few.
Mounts are able to wear equipment that grants stats and changes the appearance of the mount. For example, hoof plates increase the speed of the mount and trophies will signal to other players that you have completed a specific obscure challenge.
4.Vertical and Horizontal Movement
Diablo IV introduces both vertical movement
Achievements are called Challenges in Diablo IV and are split into different categories like Classes, Crafting, Open World, and more. Completing Challenges mainly rewards you with earning player titles.
Clans are Diablo IV's version of guilds. These come with a clan banner and bank. Clan leaderboards are being explored but are not confirmed. There are currently no plans for player or clan housing.
The game will feature an in-game voice chat, which will include clan and party voice chat.
When you die in Normal mode you will respawn, with your gear, at the last checkpoint.