The changes of this fork compared to Shattered Pixel Dungeon:

Summon weapons

You know allies from Brogue and stuff, and how strong they are? Well, it's here now, but in different fashion, more comparable to how *Terraria* does summoning. You can find 15 types of summoning weapons on dungeon's floor and try to summon a minion, which will use attunement points. Each minion has different abilities and stats, so you have plenty of variety to choose from for building your party. Each class gets one free slot at end of first dungeon zone, while summoner class has 1 innate point and gets more as he levels up.  

Minions are associated with tiering/ranking mechanic.

Tiering

The eventual solution for weapon dumps and easy endgame, the tiering is new upgrading system. If you ever pick any staff, you will notice than instead of upgrade level there is roman colored numbers. I is bronze, II is silver and III is gold. You can use Scrolls of Upgrade to increase tier of any staff (only staffs for now, other equipment will come in later patches).  

The very important note: tiers are not direct upgrades. They always take something to give you a heavy power increase. If your minion becomes sturdier and stronger, it will cost more attunement points to keep it around. If something is getting weaker, this budget goes to buff some other weapon's stats. Overall, tiering is supposed to give Scrolls of Upgrade an importance as strategic resource, as tier I (hopefully) will be enough to beat the game. You should choose tiers only if you have suitable strategy for them.

Summoner class, aka Conjurer

If there is summon weapons now, there should be a class themed around them. Meet Conjurer, the guy who is suspiciously simular to hyperdeath goat gods, and the master of divine magic. His power involves collecting soul as some sort of mana and using it for energetic spell, which can heal allies, deal damage or inflict harmful effect to your enemies. The complexity comes from tiering on spells (yes, Conjurer's spells also have tiering) and the amount of them, allowing you to manage and spend mana in countless different ways. Subclasses are focused on either offensive or defensive powers; offensive side gets its own JoJo stand!

Hunger rework

No more hunger cloak wanting to eat you in sleep! Well, not exactly. Hunger mechanic have been redone to depend from your actions: if you just sleep, you consume your satiety at far slower rate, compared to actively fighting monsters. Some food items now also grant food regeneration and food poisoning, making you think about what to cook and what to throw away. This rework also opened the way to rework Warrior, which was a tutorial class in Shattered PD.

Warrior rework

As class unlocks were removed, I wanted to bring Warrior above "the class for noobs". He now has fairly limited, but viable source of ranged damage in form of slingshot that grows with hero's strength stat and ignores target's armor partially. His seal is now applied to weapon and allow to use special attacks. Those attacks vary from weapon to weapon, but they all consume 5% of satiety, so you will have to choose from which angle you want to use those powers efficiently and not waste hunger. Subclasses can appease the fans of using consumables non-stop, or synergy-searching players who want to explore special attacks at any range.

Game modes

Find something for yourself at start of each run. Want bigger floors? Want extra hard challenge? Or you like to have distilled Hack's'Slash? All of those can be provided by game modes. They are chosen at start of each run.

New and enhanced bombs

I always felt like bombs were in awkward position, when they do moderate damage and are too rare to use them against most of mos. Now bombs deal at least 2x-3x more damage and are more frequent in dungeon. Also, all crafted bombs have been buffed of reworked. Most of them don't deal direct damage, but apply room wide area of effects, like freezing or shrinking. You can also find not a bomb, but a nuke, but its power might be too much for most of dungeoneers.

Economy changes

Everyone will be disappointed by big amount of cash doing no work in your vallet. That's why Dungeoneering Council forced all shopkeeper to expand their stock. Now you can find more useful consumables, unique weapons, full heal potion, exotic consumables and more. Sadly, the amount of gold dropped and gold used is quite inflated for today, so don't let big numbers fool you.

Endless mode

Everyone deserves to show their strength and power against dangerous monsters and eldritch horrors. Now you can ask Amulet to descend you into Abyss: the bottomless dungeon zone, where most annoying mobs will fight you to protect the reliquary: Chaosstones. Those gems are rumored to be much stronger magic than everything else in regular dungeon, maybe even more powerful than Amulet of Yendor. Can you collect several hundred Chaosstones?

Dynamic dungeon size

Find regular dungeon too expansive or too tight for your adventures? Now you can pull a global toggle to change dungeon's size for your own taste. Choose small dungeon, regular dungeon or really big mastodon dungeon with more loot and such. Pick your session time!

New arcane arts

The new 5 magical wands arrived into dungeon's rooms: wand of Conjuration (summons spectre sword, like in Brogue), wand of Crystal Shards (shoots big projectile that shatters into homing shards), wand of Shadow Beams (shoots beams that randomly bounce of walls and characters), wand of Stench (summons a toxic ghost which will spread slowness DoT gas) and wand of Stars (shoots star on the ground that can be detonated), each with their unique ability and power scaling. Also already existing magic have been touched quite a bit: wand of Lightning requires water to do massive damage, wand of Frost inflicts Frostburn and Frozen effects, wand of Magic Missile deals consistent damage, and Runic Blade can shoot a magical sword like famous Terra Blade.

New bestiary

Each dungeon zone has 1-2 new enemies and somewhat changed enemies. You can now meet stray dogs, dart-shooting snakes, soul vessel animatronics and bats made from hellish fires. Because of new monsters added, the clumping of their appearance on levels is changed between dungeon sizes. Have fun exploring and finding each enemy!

Weapon changes

Vampiric enchantment provides healing effect instead of instant heal.  

Scimitar has reduced base damage, but deals double damage each 4th time.  

Added cleaver, which is tier 2 weapon with innate Grim enchantment.  

Unstable enchantment has fitting glowing colors.

New consumables

You can either craft them (contain, enrage, elixir of rage, vial of perfume, scroll of soul energy) or find them in dungeons (scroll of attunement, mineral water, Zelda ropes).

Minor details

Water-related magical consumables now inflict wet which will mark enemy to being in water regardless if it actually stands on water.  

Missile weapons don't get consumed, if they deal bonus damage for stealth attack and are used for them.  

Final Froggits protect each 5th zone's floor, shooting pure light bolts and being required to be dead to descend.  

Damage-augmented bow's special is piercing javelin now.  

Bosses raise experience level directly instead of giving XP.  

Added an option to fill inventory from bottom side of its window, saving fingers from needless travel.  

Buffed final boss to not be total pushover.  

Added omniartifact item, which is 8 other artifacts at once. Have fun making it!