IDDC players in general avoid such themes - if they discovered them, they just switch to another character and wait 24 hours to get new theme. Yep, actually it's YALC (yet another legit cheezing) in IDDC. Wait 24 hours and then play again to get 'good' theme. I felt this situation twice when I made my past two streams:
1) https://www.youtube.com/watch?v=vQaoM-NYutU (in RUssian) got sandworm.. it was very boring to swipe corners of such lvls.
2) https://www.youtube.com/watch?v=2XuiVWrmIlM got Maze theme.. Also quite boring. (currently this video deleted by youtube error.. I've made an appeal and it would be available again after ~2 days).
So in current IDDC themes sequences system there are some crucial problems:
1) some themes are dull so much that people prefer to skip them
2) 'randomization' of such themes kinda 'broken' cause player could consider certain theme 'good' and play through it (play them till the end to kill boss and get certain 'good' artifact) or consider it 'bad' and pass it (just wait 24 hours). it's cheezing actually. It's very far away from true, TomeNET-style.
Idea considering rework IDDC themes:
1) Remove 24-hours CD for IDDC themes sequences. So every time when you go down - there is a chance to get any theme suited for your level.
2) Assign certain themes as 'major' ones, EX:
Barrow-Downs - Mordor - Dead Paths - Angband
3) Also if you go to the depth which correspond to the final depth of lvl (with dungeon boss), it's also become major (EX: at -1100 Orc Caves would become major cause Azog)
4) Assign certain chances for different themes, EX:
You are at -1100. After you use >, there is such chances:
a) Barrow-Downs (30%) // major one
b) The Orc Cave (50%) // become major cause it's near to the final boss (Azog @ -1150)
c) The Old Forest (5%)
d) The Sandworm lair (5%)
e) Mirkwood (5%)
f) Helcaraxe (5%)
It's just an example of course...
So every time when you take stairs - you do not know which theme would be there.. And it's beautiful, TomeNET-style gameplay, when you do not know what to expect at your next step...
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Conclusion:
Right now before player are going to continue IDDC-dive - he would check for theme. If it's, for example, Sandworm Lair or Maze - he has to wait 24 hours till it would change. Actually it's very simillar to IDDC-shop cheezing, when players waiting for 90% sale for days and weeks to get desirable it. It's not fun to wait to the next theme, especially if it comes to such long couldown - 24 hours... If IDDC themes sequences system would be improved, IDDC would become much more desirable option to play.
p.s.
I suppose it's quite hard to re-programm this system, so at least maybe it's possible for now to reduce IDDC-theme CD from 24 hours to 2 hours?
At least it would be possible to find good gap to play without waiting for the next day...