HyleX

May 4, 2026 · View on GitHub

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HyleX

A Hyle (Entropy) board game clone

What is this

This is an Entropy / Hyle 7 - like board game clone for Android. Play alone or with friends!

The original game “Entropy” by Eric Solomon requires two game rounds with a swap of roles in between. With HyleX, you can play alone and compete the computer with just one round by choosing a role.

Features:

  • Single Play: Compete the computer
  • Multiplayer: play against a remote opponent *)
  • Privacy: No central server**), no personalised data, no ads, no tracking
  • It's FOSS

*) You can also play against friends. Note that there is no central game server. You and your opponent must share your moves via regular messaging apps or QR codes.

**) The app uses App Links to open the app from clicking on such links, which requires a web-domain (https://hx.jepfa.de), to prove integrity of these App Links. The Android OS basically reads this JSON file and verifies that the installed HyleX app is signed with one of the well known containing certificate fingerprints (either by my own or by the one from F-Droid). Otherwise App Links won't open the app and won't perform the opponent's move.

Fore more details, see hylex.jepfa.de.

Screenshots

Show screenshots

Download

Download the app on F-Droid:

Get it on F-Droid

Download the app on Google Play Store:

Get it on Google Play

Download the latest test version here for testing: https://hyleX.jepfa.de/hylex.apk Note that you might need to delete the app storage if the app behaves incorrectly! Also, reading old messages could not work after updating.

Implementation

Single play against AI

The AI part is implemented using an optimized Minimax algorithm,see https://en.m.wikipedia.org/wiki/Minimax. It performs up to 4 rounds ahead, limited by the CPU power of the current device.

Multiplayer

Exchanging moves between remote players happen "out-of-band", i.e. there is no central server involved. Instead, moves etc. are encoded as URLs allowing to share and open them directly with the HyleX app. These URLs can be shared through any medium, like messengers, email, QR codes etc. So transport is not handled by this app. Later there is an idea of incorporating Veilid to share these URLs to remote players.

Invitation state transitions

How to read:

Boxes are PlayStates, arrows are allowed transitions. Text on arrows are Operations triggering the transitions.

->Operation means an incoming/received operation from a message. Operation-> means an outgoing/sent operation from a message.

State model from the perspective of an invitor (initiator of an invitation):
stateDiagram-v2

    [*] --> RemoteOpponentInvited: SendInvite->
    RemoteOpponentInvited --> RemoteOpponentAccepted_ReadyToMove: ->AcceptInvite
    RemoteOpponentInvited --> InvitationRejected: ->RejectInvite
    InvitationRejected --> [*]
    RemoteOpponentAccepted_ReadyToMove --> WaitForOpponent: Move->
    RemoteOpponentAccepted_ReadyToMove --> Resigned: Resign->
    ReadyToMove --> WaitForOpponent: Move->
    WaitForOpponent --> ReadyToMove: ->Move
    ReadyToMove --> Lost: Move->
    ReadyToMove --> Won: Move->
    ReadyToMove --> FirstGameFinished_WaitForOpponent: Move->
    ReadyToMove --> Resigned: Resign->
    WaitForOpponent --> Lost: ->Move
    WaitForOpponent --> Won: ->Move
    WaitForOpponent --> FirstGameFinished_ReadyToSwap: ->Move
    WaitForOpponent --> OpponentResigned: ->Resign    
    FirstGameFinished_ReadyToSwap --> ReadyToMove
    FirstGameFinished_WaitForOpponent --> ReadyToMove: ->Move
    Lost --> [*]
    Won --> [*]
    Resigned --> [*]
    OpponentResigned --> [*]
State model from the perspective of the invitee (receiver of an invitation):
Invitee has to perform first move:
    stateDiagram-v2
    
        [*] --> InvitationPending: ->SendInvite
        InvitationPending --> InvitationAccepted_ReadyToMove
        InvitationPending --> InvitationRejected: RejectInvite->
        InvitationRejected --> [*]
        InvitationAccepted_ReadyToMove --> InvitationAccepted_WaitForOpponent: AcceptInvite(with move)->
        InvitationAccepted_ReadyToMove --> Resigned: Resign->
        ReadyToMove --> WaitForOpponent: Move->
        InvitationAccepted_WaitForOpponent --> ReadyToMove: ->Move
        WaitForOpponent --> ReadyToMove: ->Move
        ReadyToMove --> Lost: Move->
        ReadyToMove --> Won: Move->
        ReadyToMove --> FirstGameFinished_WaitForOpponent: Move->
        ReadyToMove --> Resigned: Resign->
        WaitForOpponent --> Lost: ->Move
        WaitForOpponent --> Won: ->Move
        WaitForOpponent --> FirstGameFinished_ReadyToSwap: ->Move
        WaitForOpponent --> OpponentResigned: ->Resign    
        FirstGameFinished_ReadyToSwap --> ReadyToMove
        FirstGameFinished_WaitForOpponent --> ReadyToMove: ->Move
        Lost --> [*]
        Won --> [*]
        Resigned --> [*]
        OpponentResigned --> [*]
Invitee has to await first move from invitor:
    stateDiagram-v2
    
        [*] --> InvitationPending: ->SendInvite
        InvitationPending --> InvitationAccepted_WaitForOpponent: AcceptInvite->
        InvitationPending --> InvitationRejected: RejectInvite->
        InvitationRejected --> [*]
        InvitationAccepted_WaitForOpponent --> ReadyToMove: ->Move
        InvitationAccepted_WaitForOpponent --> OpponentResigned: ->Resign
        ReadyToMove --> WaitForOpponent: Move->
        WaitForOpponent --> ReadyToMove: ->Move
        ReadyToMove --> Lost: Move->
        ReadyToMove --> Won: Move->
        ReadyToMove --> FirstGameFinished_WaitForOpponent: Move->
        ReadyToMove --> Resigned: Resign->
        WaitForOpponent --> Lost: ->Move
        WaitForOpponent --> Won: ->Move
        WaitForOpponent --> FirstGameFinished_ReadyToSwap: ->Move
        WaitForOpponent --> OpponentResigned: ->Resign    
        FirstGameFinished_ReadyToSwap --> ReadyToMove
        FirstGameFinished_WaitForOpponent --> ReadyToMove: ->Move
        Lost --> [*]
        Won --> [*]
        Resigned --> [*]
        OpponentResigned --> [*]

Play state transitions

How to read:

Boxes are PlayStates, arrows are allowed transitions, indicating the direction. Text on arrows are Operations triggering the transitions.

Sequence flow if an invitation gets rejected:
sequenceDiagram

    actor Local as Invitor
    actor Remote as Invitee

    Local->>+Remote: <SendInvite>
    Note over Local: [RemoteOpponentInvited]
    Note over Remote: [InvitationPending]
    Remote-->>-Local: <RejectInvite>
    Note over Local: [InvitationRejected]
    Note over Remote: [InvitationRejected]
Sequence flow if an invitation gets accepted:
sequenceDiagram

    actor Local as Invitor
    actor Remote as Invitee

    Local->>+Remote: <SendInvite>
    Note over Local: [RemoteOpponentInvited]
    Note over Remote: [InvitationPending]


    alt Invitor starts
        Remote-->>-Local: <AcceptInvite>

        Note over Remote: [InvitationAccepted_WaitForOpponent]
        Note over Local: [RemoteOpponentAccepted_ReadyToMove]

    else Invitee starts with initial move

        Note over Remote: [InvitationAccepted_ReadyToMove]
        Remote-->>Local: <AcceptInvite with Move>
        Note over Remote: [InvitationAccepted_WaitForOpponent]


        Note over Local: [RemoteOpponentAccepted_ReadyToMove]
    

    end



    loop actual play
        Local->>+Remote: <Move>
        Note over Local: [WaitForOpponent]
        Note over Remote: [ReadyToMove]


        Remote->>-Local: <Move>
        Note over Remote: [WaitForOpponent]
        Note over Local: [ReadyToMove]
    end

License

HyleX / Hyle X - An Entropy clone

Copyright (C) 2026 Jens Pfahl

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.