Spin up Ubuntu 12.10 x64 droplet:

Step 1 - Install LAMP stack
export DEBIAN_FRONTEND=noninteractive apt-get -y install apache2 mysql-server mysql-client php5 php5-mysql php5-gd imagemagick
Step 2 - Create A Database
We will create database 'phpBB' and user 'phpBB' with password 'PassWord', make sure to change it to your own value:
mysqladmin create phpBB mysql -Bse "create user 'phpBB'@'localhost' identified by 'PassWord';" mysql -Bse "grant all privileges on \`phpBB\`.* to 'phpBB'@'localhost';" mysqladmin flush-privileges
Step 3 - Install phpBB
You can find latest version of phpBB from their website. We will download latest version and copy it over into Apache's default folder:
wget https://www.phpbb.com/files/release/phpBB-3.0.12.zip unzip phpBB-3.0.12.zip rm -rf /var/www/* cp -R phpBB3/* /var/www/
Set Correct Directory and File Permissions
cd /var/www for files in config.php cache files store images/avatars/upload/; do chmod 777 $files; done
Step 4 - Finish Installation
Navigate over to http://IP/install (http://198.199.92.189/install/ in our case):

Click on 'Install' tab:

You should have all the required packages already installed:

Enter Database Credentials, replacing PassWord with your own value:
Database type: MySQL with MySQLi Extension Database server hostname or DSN: localhost Database name: phpBB Database username: phpBB Database password: PassWord

If you set it up correctly, you should see a successful database connection:

In this next step you should setup your admin username and password:

Setup E-mail settings if you have a custom SMTP server, otherwise stick with the default values:

Your installation should now be (almost) complete:

Delete /install Folder
After you are done installing phpBB you should delete /install folder:
rm -rf /var/www/install
Now you should be able to access your phpBB forum at your droplet's IP address:

To access admin interface, click on "Administration Control Panel" at the bottom of the page:

And you are all done!