Alright, some things I'm considering for the next contest (and possibly future ones, depending on how well it works out), based on existing feedback etc - feel free to discuss these, as they aren't "finalized" until the contest begins.
1. Lix
If there is nothing inherent in the criteria that would prevent a Lix level from meeting it, single-player Lix levels will be allowed in addition to Lemmix / NeoLemmix / Lemmini / SuperLemmini. In the case that rules make reference to the "original 8 skills" in any way, the non-flinging bomber is the one that counts as part of this. Unless contest rules state otherwise, Lix-exclusive features/skills are permitted. Multi-player Lix levels are not permitted, unless the contest rules specifically state otherwise.
2. Revision of levels
Revised version of the levels will be allowed during the playing phase, and the playing phase will most likely be extended to account for this. How this will work is that during the playing phase, there'll be several extra "deadlines", and at each of these, if updated levels have been received, they'll be posted (along with an announcement that updated versions are available). You can submit as many updates as you like until the final update deadline has passed (which will be at least a few days before the voting phase starts); the newest one prior to the deadline will be uploaded as each deadline passes. Once the final deadline has passed, no further updates can be submitted - the level will have to enter the voting phase as-is, though as usual you're free to update it again once the contest has ended.
3. Custom graphics, VGASPECs
This is more just a change in formatting than anything else; but from now on, it will not be explicitly mentioned that these are allowed. Instead, it will only be explicitly mentioned if they're not allowed - if nothing is mentioned about them, assume they're fine. The rule still stands that if using a custom graphic set, you must provide a copy of it with your entry, unless it's included by default with the engine (eg. if you make a NeoLemmix level using one of the Lemmings Plus graphic sets, you don't need to include that, as NeoLemmix includes the LP sets by default).
4. Closing dates
There'll be a minimum closing date, which will be a similar timeframe to in the past (about two weeks). However, on top of this, even after this date passes, entries will not close until 72 hours since the last entry was received (or one week since the last entry was received, if there are less than four entries so far).
5. Minimum number of entries
Entry period will no longer extend if the contest has not reached four entries. The contest will immediately be cancelled if only one or two entries have been received. If three entries have been received however, it will proceed as normal, except only first place will get a prize (instead of both first and second).