This patch adds new Random Events to the game that aren't possible with the current RandomEvents table. This patch includes, and supercedes the old StarlaneEvent patch. The patch currently adds three new Random Events to the game - the aforementioned Starlane Event, a new AntaranRevolt Event, and a new DiscoverSystem Event.
The Starlane Event adds the possibility of 'new' starlanes being created. 'New' is in quotations because they aren't properly new at all. During galaxy creation, a pool of starlanes for each system is created. From this pool, some are chosen to be starlanes, and some are not. But even the ones that are not are stored. This patch selects one of these unchosen lanes, and turns it into a normal starlane.
The AntaranRevolt Event does what it's name describes - causes an Antaran Revolt to take place in the New Orion empire. This causes the destruction of the New Orions (if they exist at that point), and the creation of a new empire formed by the citizens from the old empire. This new empire acts just like an AI empire - meaning they will expand, enter wars, etc. Depending on when this event takes place, it can dramatically alter the course of a game.
Finally, the DiscoverSystem event will cause a random empire to 'discover' (or, more accurately, explore) a random unexplored system, assuming such a system exists. This will cause them to become aware of both the planets in the system, and any starlanes.
The ExtraRandomEvents.txt file included with the patch controls the chance of each event taking place on any given turn. This file should be placed in your main MoO3 directory. The 'Chance' column is a value from 1-1000, where 1000 means the event will take place every turn, and 1 means there is a 0.1% chance of it taking place. For the mathematically inclined, setting the 'Chance' to 7 will mean that the event has a 50% of happening in the first 100 turns. If you don't want a particular event to take place, you can either remove that row from the file (not recommended), or simply set the chance to '0' (recommended).
Also included with the patch are sample Sitrep.txt and wsSitrep.txt files. These are necessary for the events to be reported properly. If you use custom Sitrep files, then you will need to copy the last 3 entries from each file into your own.