Chess on 2 devices

This is a dual-player chess game developed by MFP programming language. This game requires two players, using different Android devices but running the same software. There is no need for a central server to play this game. Two Android devices communicate point-to-point through TCPIP protocol or WebRTC protocol based on email addresses.
If you use the TCPIP protocol, the two devices are not required to sit inside the same gateway. NAT layer in between is acceptable. When the game starts, the IP address of the device will be displayed. The player who starts the game first must tell the other party the IP address of the machine, and then the second player enters the IP address of the first player to connect. If the connection is built up successfully, the game will start.
If you use the email address based WebRTC protocol for point-to-point communication, you can play with the other party thousands of kilometers away. The process to start the game is similar to using the TCPIP protocol. After the first player starts, wait for the second player to start and enter the email address of the first player to connect. If the connecting attempt is successful, the game will start. But different from TCPIP, the first time you use the WebRTC protocol for peer-to-peer communication, you need to set the e-mail address of the machine. You need to enter the email address and password in the setup (note that this is the password used when sending and receiving emails with SMTP and IMAP protocols, it is not necessarily the same as the password used to login the webmail). If you are using Microsoft Outlook mailbox, Tencent QQ mailbox, yahoo mail or Google gmail mailbox, you do not need to enter other information, otherwise you need to enter smtp and imap server information. In addition, users also need to make sure that SMTP and IMAP services have been turned on and that the other party's email address will not be blacklisted, which means the other party's signal emails will not be treated as spam).
When using an email address for peer-to-peer communication for the first time, some mail service providers, such as Google, will detect the APP sending the email and block this APP because it sends emails using free SMTP and IMAP protocols instead of paid GMail APIs. A critical security alert will be sent to the Gmail address. User simply needs to confirm this is a valid activity and turn on "Allow less secure apps" function. Microsoft is more open to SMTP and IMAP protocols. However, if user switches network or devices too frequently, Microsoft may also block user from sending email. In this case, Microsoft will send user a notice. And user needs to login Outlook webmail and confirm these are valid activities.
After setting up WebRTC protocol, no need to change it. Then two players who are far away can play chess against each other as if they are in the same room at any time. Furthermore, this version of the game has started to support video and voice communiction. As such players can chat with each other when they are playing the game.