These are the main sites where you can find more help:
Simutrans is in constant development and you can find bugs.
The game is crashing, flickering or having input problems? Report in Bug Reports.
Graphical problems, wrong vehicle speeds or any other data regarding game objects? Report in the subforum of the pakset.
Any problem with our sites? Report in Web & Wiki.
Simutrans is a modular game, the executable and the game data are separated.
A 'pakset' is what we call the data set that Simutrans needs to run. It contains all the data for the graphics, the individual items (vehicles, roads, railways, buildings and others) and all of the balancing information (such as prices, speeds, capacities and so forth) necessary to make the game complete.
They are called 'paksets' because all the files are compressed (from German 'Paket') to save space as a pak file. Paksets also determine the size of the graphics used, this number is the height and width of one tile in pixels. This size generally is shown at the start of the pakset name, for example, pak64 has tiles with 64px, while pak128 has tiles with 128px. Some paksets don't show a number in their names, but they always state the size when describing the pak.
Simutrans has a large and growing number of paksets, many with specific themes such as pak96.Comic or pak128.Britain. To find more about Simutrans many individual paksets, check the Paksets Page
Simutrans is not bound to a specific scenario data, you can choose the paksets you want. We don't set any pakset as a standard.
Yes and No. There are three main things that lead to an incompatible addon:
There are a number of differences between Simutrans and OpenTTD. The people developing Simutrans focus on different tasks. One of the most notable difference is that cargo, mail and people have destination. Each factory has fixed contracts with just some other factories and won't send or receive cargo from other factories, people want to go and send mail only to some locations.
If you are coming to Simutrans from OpenTTD check our wiki article with the most notable differences.
The PAK file was created to protect the rights of the creator of the file. It was designed specifically not to be unpacked for such reason.
However, take heart! If you can find the original creator, most of the time they would send you some sort of source if they still have it (but if they do not, that is their firm right).