Quarkchain is 3rd generation blockchain (Bitcoin = 1st, Ethereum = 2nd). They are planning to solve scalability issues.

With innovative blockchain structure, they believe that platform will be able to support: distributed social media, high-frequency trading, Internet of Things (IoT), gaming and financial payments.

Main features of QuarkChain

Reshardable two-layered blockchain
Guaranteed security by market-driven collaborative mining
Anti-centralized horizontal scalability
Efficient cross-shard transactions
Simple account management
Turing-complete smart contract platform

Reshardable two-layered blockchain

The QuarkChain Network contains an elastic sharding blockchain layer, which contains a list of minor blockchains (shards). Each shard processes a sub-set of all transactions independently.

It has the root blockchain (rootchain) that confirms all blocks from sharded blockchains. The root blockchain does not process any transactions, but its block has sufficiently strong difficulty so that reverting any transactions is not economically efficient.

It is designed so that adding more shard is easy and fast and the users barely sense this.

Guaranteed security by market-driven collaborative mining

The goal of collaborative mining is to design incentive mechanisms and difficulty algorithms so that

Hash powers are incentivised to distribute evenly among shards
The root chain has a significant large portion (over 50%) of hash power over the whole network

Each shard acts like a separate blockchain for mining which rewards miners for mining. Each shard offers different incentives and difficulties. It is desirable that a marketing model is designed with features ensuring that though each party in the market pursues their own interests and the collective behaviors of each party can benefit all.

Consensus algorithm

The root chain runs the POW algorithm
Each shard runs a consensus called root-chain-first POW algorithm

This prevents double-spending because attacker has to create:

The minor blocks that revert the transaction
A longer root chain fork that includes the minor block headers

Such attack is hard to perform because attacker must acquire at least 50% (hash power on root chain)*51% = 25% hash power of overall network.

Anti-centralized horizontal scalability

As running a super-full node could be very expensive in a high-throughput network, Quarkchain will allow multiple honest nodes in a cluster to run a super-full node.

For encourage forming such clusters, Quarkchain will have incentives for miners to answer a puzzle about the information of random blocks.

Efficient cross-shard transactions

Quarkchain transactions can be classified into two categories

In-shard transactions
Cross-shard transactions

Cross-shard transactions are more difficult because of the synchronization between two shards. The Quarkchain Network fully supports cross-shard transactions as first-class citizen, in a sense that:

Any user could issue any cross-shard transaction at any time
Cross-shard transactions can be confirmed in minutes
The throughput of cross-shard transactions could be scaled linearly as the number of shards increases

Simple account management

A user only needs to have one account to manager all addresses in all shards and perform transactions. Smart wallet will automatically perform cross-shard or in-shard transactions (including smart contracts) for user, and the user may
not be even aware of sharding in the system.

Turing-complete smart contract platform

Quarkchain will support smart contracts via Ethereum virtual machine (EVM). Most of the existing dApps built on top of EVM can be directly deployed on the Quarkchain platform.

This is the brief overview of Quarkchain main features. If the QuarkChain team delivers, it could be one of the leading blockchain network.

It is just my opinion — not investing advice.