I'm still new to this game, only cleared it like 5 times in solo mode. Please comment if there are more information that I missed!

Hope its sufficient enough information for newbies to get started.

Gameplay video: https://www.youtube.com/watch?v=2--uB1cNoaw

Information window summary: https://imgur.com/a/IEZXx1k

Here are some tips:

Hero
1. Equip at first slot is your weapon that can be leveled up. When it hits the required kill count, you can "use" it to teleport to fight a boss to level it up. At max level, it can be consumed to gain a boost to your stat.
2. You can merge items by clicking the first icon above the first item slot. 3 lower rarity merges into 1 higher rarity (three 1-star becomes one 2-star). Can also be done by your pet, as described below.

Pet
1. Use your pet, the Jade Roshan is free
2. Pet W to pick up items in targeted area
3. Pet E to drop items in targeted area
4. Pet D to send items in area into Proving Ground. Books will automatically be on the left, and equips on the right. Other items go to center bottom.
5. Pet R to merge items in that area. You can merge books and equips into higher rarity.

Treasure map
If you have this, using it will teleport u to a place with X marks on the floor. Stand on the X mark and use the map again.

Quick guide

1. Buy the axe from the Farmer(Panda) merchant on the left in the Proving Ground. You'll farm faster!

2. Do your quests (top right "GO TO" button) when you're strong enough. You gain stat boosts.

3. Upgrade your weapon (first item slot) when its kill count is not increasing anymore. You gain stat boosts.

4. Proving Ground Instructor: You can upgrade the creep level when you're stronger. If you die to the creeps, just lower the creep level back. You can click the last icon in this instructor to fight a morphling, which gives u an equip chest upon defeating it.

5. Vulcan forging: Spend your resources here to upgrade your stats. Press Q to auto upgrade as many as possible, or spam W to upgrade one by one manually. It costs gold at the start, but after a few upgrades, sometimes it costs crystals (blue mats) or honor (purple mats).

6. Farmer: Panda sells a water can that u can buy and hold it on your courier. It flowers seeds to make them grow faster. It also sells seeds which u can purchase when you have gold, use the seeds on the ground. After the seeds mature into a plant, use your pet "W" on the plants to collect your rewards.

Panda also sells a fishing rod, which you can give to the panda near Athena (left-bottom her), then the panda will automatically fish for you.

7. Maze of Apparition: Storm spirit teleports u to little rooms with bosses that can be farmed. Takes about 15 seconds to respawn. You should farm them to get [Blessing Tx]. You can check the blessings available and those you have obtained, in the icon beside your hero portrait at the bottom of the screen. There are 3 types of blessings per tier.
- Lifestealer drops T1 Blessing
- Arc warden drops random equips
- Visage (3rd icon) drops T2 Blessing
- Bane drops consumables that buff stats, and gives crystals upon killing. Farm this when you need crystals to upgrade from Vulcan forging NPC.
- Viper drops T3 Blessing
- Pugna room drops T4 Blessing (from Terrorblade or Shadow Fiend). Pugna drops random equips.
- Abaddon drops T5 Blessing
- Doom drops random equips, Pit lords gives crystals upon killing. Farm this when you need crystals to upgrade from Vulcan forging NPC.
- Zeus drops T6 Blessing.

8. Ares' Palace: This shop lets you spend honor to upgrade various stats. Not sure whats optimal, I'm just spamming honor rate early on so I get farm honor quicker to upgrade the other stats.

9. Tyche's Follower: When you have excess gold, spend it on this guy to get random stat buffs / items.

10. When you're level 100, the Proving Ground Instructor's last icon will become "Awakening" (42:55). Upgrade some HP regen from Ares' Palace to make sure u survive the lava.

11. Blessed Gem (Purple orb): Use it on a 6* item to consume it. You'll get its stats on your hero without wasting an item slot.

12. Excess crystals, spend them on Tyche's Follower. These items are locked at first, and can be unlocked by "using" it to consume another 6* item. You'll get its stats on your hero without wasting an item slot.

Extra content
At the left side of Athena, there are a group of bandits that you can farm for treasure maps!