Ren’Py can definitely branch-and-bottleneck. Unless otherwise specified, every code snippet below should be at the same number of tabs as whatever was above it. Also note that my instructions are for Ren’Py 7 - the ones for Ren’Py 8 may be the same, or they may be slightly different. Some of this may seem really basic, but each step is being built upon.
To directly send a player to a scene:
label blobpart
(content)
scene othersplatpart
If you’re wanting to bottleneck from several branches, simply make sure every scene you wish to bottleneck ends with the same scene as “othersplatpart”, and then have a section that starts with “label othersplatpart”.
To branch by choice:
menu:
[tab] Choice 1:
[2x tabs] Consequences of choice 1, usually ending in a scene command as discussed above
[tab] Choice 2:
[2x tabs] Consequences of choice 2, usually ending in a scene command as discussed above
(the next bit should go back to the same number of tabs as the "menu:" command).
To branch by quality / skill / attribute / event flag / other thing set by a specific other event
At the beginning, you need:
default gloop = False
default points = 0 default colour = Inapplicable`
Note that “something” can be True or False (useful for event flags), a number (useful if you’re planning to add, subtract or otherwise do maths on it) or letter(s) (handy if, for example, you’re using it to record a location).
There should be at least one opportunity to change that “default” if branches or bottlenecks will depend on this. Make that happen by doing one of the following:
$ gloop == True
$ gloop == False
$ points == 3
$ points += 2
$ points -= 1
$ colour == Green
Note that the dollar sign means this is a line of Python. After that is the name of the attribute affected. The first sign after the attribute name states what’s being done with it. Equals means “the attribute is”, + means “the attribute is being added to” and - means “the attribute is being taken away from”. The second equals tells the program… …something. Not sure what, but it’s compulsory. Also, letters are case-sensitive.
When you need it, you can use if-then statements to control the movement through the work:
if gloop == True:
[tab] $ points += 1
[tab] scene happyending
else:
[tab], scene nextscene
Make sure whatever comes next is written at the same tab level as “if:” or “else:”.
Note that it’s also possible to compare an attribute with a preferred target. Ren’Py uses “less than” and “more than”:
if points >= 5:
[tab] You return from the swamp to be greeted by jubilant villagers, and hold aloft you [colour] gloop in triumph. Within a year, your village has become a local centre for excellence in gloop searching because of the guidance you gave your fellow villagers on the topic.
elif points <= 2:
[tab] You briefly consider returning to your village, but you could really do with more gloop.
elif points == 5::
[tab] You return to your village with enough gloop to repair your neighbour's wall as well as your own. A fine friendship develops over the next few months, due to your habit of walking to the swamp every week to spot aesthetically pleasing examples.
else:
[tab] You have enough gloop to go home, fix that unsightly hole in your wall and enjoy a nice cup of tea by the fire.
In order to have something happen randomly:
$ randomnum = renpy.random.randint(1,4)
The “randint” part means only whole numbers can be selected. The numbers in the brackets are the smallest and largest numbers that can be randomly selected.
Later, you simply use “randomnum” as an attribute, as if it was the non-random “gloop” or “points” earlier.
How to make a menu choice only appear if certain choices are met:
menu:
[tab] Wade into the swamp again if points <=6:
[tab x2] Consequences of wading into the swamp again
[tab] Emerge triumphant if gloop == True:
[tab x2] Consequences of emerging triumphant
There are a few other pieces of code that would be useful to you, but it's possible to get some content not appearing on every playthrough just with these code snippets and the easier parts of the Ren'Py tutorial that comes with the Ren'Py download. The [official documentation](https://www.renpy.org/doc/html/) has lots more bits of code to experiment with, and I'm happy to answer more specific questions.