(unashamed promoting)
quest text adventure (UK based):
it's free/public (including commercially too!, and can host your games where-ever you want too), great for text games, and can add images too, very very powerful engine (if good programmer, you can create your own engine! Also, very powerful coding capability for your game making) with a lot of built-in useful features already and more being added too, including having a GUI/Editor for non-coders, and its coding is very easy to learn, and while the community is small, we're very helpful (active forum and posts for our small community), and along with there being lots of resources/guides too. We already got some people using it to make adult (and fenoxo/coc/tits-like/inspired) games, especially our user 'anonynn' and his/her 'apocamorphosis' game. I've not played it yet, but she/he pumps out a lot of writing/coding, with a very high word count, and he/she is learning to code in more and more fancy stuff, starting from not knowing too much about coding. Quest games can be played offline (have to download the quest.exe engine/software to play them) or online (has maintained servers, that you can upload/publish your games to and/or play games without needing to download the quest.exe engine/software)