It should be installable.

[akovalyov]

$ composer global require umpirsky/centipede:0.1.*@dev

ends with the following error

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - umpirsky/centipede-crawler 0.1.0 requires react/promise dev-master@dev -> no matching package found.
    - Can only install one of: guzzlehttp/guzzle[5.3.0, 4.1.3].
    - Can only install one of: guzzlehttp/guzzle[5.3.0, 4.1.3].
    - Can only install one of: guzzlehttp/guzzle[5.3.0, 4.1.3].
    - umpirsky/centipede-crawler 0.1.1 requires guzzlehttp/guzzle ~5.3 -> satisfiable by guzzlehttp/guzzle[5.3.0].
    - umpirsky/centipede 0.1.x-dev requires umpirsky/centipede-crawler ~0.1 -> satisfiable by umpirsky/centipede-crawler[0.1.0, 0.1.1].
    - Installation request for umpirsky/centipede 0.1.*@dev -> satisfiable by umpirsky/centipede[0.1.x-dev].
    - Installation request for guzzlehttp/guzzle == 4.1.3.0 -> satisfiable by guzzlehttp/guzzle[4.1.3].

However it is related to the centipede-crawler, I decided to open it here as the whole project is not installable.

[umpirsky]

Worked for me:

$ composer require umpirsky/centipede:0.1.*@dev
You are running composer with xdebug enabled. This has a major impact on runtime performance. See https://getcomposer.org/xdebug
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Installing react/promise (v2.2.1)
    Downloading: 100%         

  - Installing guzzlehttp/streams (3.0.0)
    Downloading: 100%         

  - Installing guzzlehttp/ringphp (1.1.0)
    Downloading: 100%         

  - Installing guzzlehttp/guzzle (5.3.0)
    Downloading: 100%         

  - Installing umpirsky/centipede-crawler (0.1.1)
    Downloading: 100%         

  - Installing symfony/console (v2.7.7)
    Downloading: 100%         

  - Installing umpirsky/centipede (dev-master 1d9bfb1)
    Cloning 1d9bfb16fac77b885f243c0342089c372f5ea2af

symfony/console suggests installing symfony/event-dispatcher ()
symfony/console suggests installing symfony/process ()
symfony/console suggests installing psr/log (For using the console logger)
Writing lock file
Generating autoload files