The last time I installed OpenTTD, I got put off by having to download various files for different AIs. Is this still the case now? Or does OpenTTD now come with some standard AIs by default, just like when the game originally came out on DOS? Is it worth trying OpenTTD again, or just sticking with my DOSBox installation of the original game?
OpenTTD ships with the following: core game files, OpenGFX (graphics), OpenSFX (sound effects), and OpenMSX (in-game music). All other content (AIs, game maps, scenarios, NewGRFs, game scripts) can be automatically downloaded through the in-game content download service. Almost all current mods are now released by contributors through this service, you no longer need to go to the forums or other websites and download individual files.
If you've not played OpenTTD in the last 3-5 years, then you may be pleasantly surprised by all the new features that have been added. Up to 64 types of rail lines, roads and tram lines; up to 128 types of industries that can accept/receive 16 types of cargoes each; support for 32bpp graphics and extra zoom level graphics; improved interfaces, improved game mechanics, better vehicles management. Contributors are continually finding new ways to exploit and expand features. And since OpenTTD's code base moved to GitHub last year, significantly more people have been able to provide patches, suggestions and bug fixes that have been adopted and implemented. Part of that change is why OpenTTD is now available on GOG and Steam, and anytime the core game is updated, those platforms automatically get those updates within hours, if not minutes.