Evaluating Generalisation in General Video Game Playing
  The General Video Game Artificial Intelligence (GVGAI) competition has been
running for several years with various tracks. This paper focuses on the
challenge of the GVGAI learning track in which 3 games are selected and 2
levels are given for training, while 3 hidden levels are left for evaluation.
This setup poses a difficult challenge for current Reinforcement Learning (RL)
algorithms, as they typically require much more data. This work investigates 3
versions of the Advantage Actor-Critic (A2C) algorithm trained on a maximum of
2 levels from the available 5 from the GVGAI framework and compares their
performance on all levels. The selected sub-set of games have different
characteristics, like stochasticity, reward distribution and objectives. We
found that stochasticity improves the generalisation, but too much can cause
the algorithms to fail to learn the training levels. The quality of the
training levels also matters, different sets of training levels can boost
generalisation over all levels. In the GVGAI competition agents are scored
based on their win rates and then their scores achieved in the games. We found
that solely using the rewards provided by the game might not encourage winning.
