Click any dot to show all related activity. Hover on a dot to see the details of the tweet. You can change the sizes of the dots - see Settings below.
Many of the elements in a tweet are clickable: name, date, hashtags, urls, mentions. The buttons on the right of a tweet let you share or fave it.
Click on a date divider to focus all tweets for that day. Similarly, click on a count divider to focus on a block of 1000.
Use the right nav to re-order the tweets. The order that you re-order matters. Give this a try: order by Retweet count, then re-order by Kind.
Click the gear icon in the left nav to access the settings. You can set the minimum and maximum dot size, and change the colour scheme.