Diamond Dash

position: senior backend engineer
a game with millions of daily active users
rewriting the backend from PHP code base to Ruby on Rails
writing tests while reverse engineering the PHP code base
improving the deployment process which was completely manual before
profiling and optimizing code
optimizing SQL queries (dataset ~ 50GB)
datacenter / provider migration incl. DB with minimal downtime of few minutes
writing payment validation and push notification service for iOS clients in Erlang

Bubble Island

position: senior backend engineer
a game with millions of daily active users
rewriting the stateless PHP backend to a stateful Erlang backend and drastically reducing DB access and app server CPU usage
writing tests while reverse engineering the PHP code base
writing a ORM in Erlang for the existing sharded DB
writing a small test framework for Erlang which I use for about every project (https://github.com/wooga/etest)
datacenter / provider migration incl. DB with minimal downtime of few minutes
switching from Linux (Gentoo) to FreeBSD as server OS
choosing servers, provisioning servers, network setup, database server setup
writing/improving payment validation and push notification service for iOS clients in Erlang

position: senior backend engineer
A real time multiplayer bomberman prototype to test the feasibility of mobile games with multiplayer features (over 3G), written in Erlang
designed and implemented a highly optimized UDP protocol for client/backend communication

position: senior backend engineer
central piece of infrastructure based on Kafka, collecting and processing tracking calls for all games of the company
switching from a low performance and high cost cloud setup to a high performing low cost dedicated server setup
survey of suitable datacenters
choosing a rack full of hardware for brokers, consumers, databases and loadbalancers
planning of a fully redundant network setup including CARP and manual datacenter failover to a different location and 10Gbit internal networking
setup of redundant loadbalancers based on haproxy for thousands of requests/s including SSL/TLS termination
all servers based on FreeBSD with Jails and ZFS, provisioned with Ansible
gradual datacenter / provider migration incl. data with no downtime

position: senior backend engineer
a game with millions of daily active users
maintaining, documenting and improving the code base, writing new features in Ruby

position: senior backend engineer
new game, backend written in Erlang with PostgreSQL as database
implementing a highly relational and complex data model optimized for performance
researching the implementation of football simulators
implementation of various statistical distributions in Erlang (poisson, normal, exponential, truncated normal, discrete probability) based on reference papers and C implementations from R (https://github.com/hukl/rstats)
implementing schedule creation, league progression, simulation loop and various busines logic for football and for potentially millions of users
running on dedicated servers with FreeBSD using Jails, provisioned with Ansible
training / onboarding 2 frontend developers to become backend developers

switching the company's CDN provider and supporting the migration of games to the new CDN
consolidating a zoo of SSL certificates by migrating them to one provider and supporting the migration of various services
helping to manage the company's DNS setup
interviewing new candidates (~60+ screening calls and ~20+ on site interviews)
consulting other teams on infrastructure / technology decisions