Tutorials

Install XBoard with RodentII chess engine

How to install XBoard with the RodentII chess engine on Linux/Ubuntu:

  1. sudo apt-get install polyglot xboard
  2. git clone https://github.com/nescitus/Rodent_II.git
  3. cd RodentII/sources
  4. make
  5. sudo make install
  6. add xboard to favorites and start it
  7. load new engine #1 with the following settings:
    1. engine directory: /usr/bin
    2. engine command: rodentII
    3. also make sure to enable the UCI protocol

How to change the skill level of the RodentII chess engine:

  1. The default skill level of RodentII is equivalent to the maximum available skill of a Grand Master (ELO 2600–2800)
    1. Hence it is not suited for playing against it as a beginner, because it will just thrash you even during the initial opening and will punish the slightest almost unoticeable mistake that even stronger players will inevitably make
  2. We can control the skill level of RodentII with the engine #1 settings
    1. The setting with the most influence on the skill level is NpsLimit (Nodes per second Limit), which throttles the computational power of the engine
      1. To make the engine weaker by slowing it down, we therefore change this setting from 0 (unlimited) to 1 (minimum):
    2. The next important setting with influence on the skill level is EvalBlur, which adds a random value on the evaluation function
      1. To make the engine weaker by assessing the situation more fuzzy, we therefore change this setting from 0 (no fuzziness) to 300:
  3. This will result in a performance equivalent to a novice player (ELO 250)
  4. Improving performance from that base line is possible with the following settings:
    1. A setting of NpsLimit to 10 and EvalBlur to 100 will result in an average player (ELO 500–600)
    2. A setting of NpsLimit to 100 and EvalBlur to 50 will result in a strong player (ELO 1000–1200)
    3. A setting of NpsLimit to 1000 and EvalBlur to 0 will result in a very strong player (ELO 1500–1600)
    4. A setting of NpsLimit to 3000 and EvalBlur to 0 will result in a player that will defeat even experienced players (ELO 1800–2000)
  5. If you have been learning the chess rules and basic chess logic, it is still way better and more fun to play against humans. They just play differently than computers!

To remove the RodentII chess engine:

  • sudo make remove

Options: