I have added definitions for the secret ending and 100% categories of the game, extrapolating from the current timing definition of the any% (now any% normal ending) and from what the game considers completion of those objectives.

100% COMPLETION

In Venineth there are 11 main levels, each with four hidden collectibles. After finding 3, 9, 15, 24, 33, or 42 of those collectibles, Venineth unlocks one of its six secret levels (Trinoids). Following the maxim that 100% completion of a game consists of completing all levels and collecting all collectibles, it is natural to consider "44 collectibles, 17 levels, and both endings" the definition of 100% for Venineth.

Since it is impossible to obtain the normal ending without beating the 11 main levels and the final main minilevel, and it is also imposisble to obtain the secret ending without being the six secret levels and the final secret minilevel, it is impossible to satisfy both the "44 collectibles" requirement and the "both endings" requirement without also completing all 17 levels.

A potential alternative definition of 100% may consist of collecting all 32 Steam achievements. However, 29 of these achievements are necessarily collected over the course of my 100% definition proposal. The remaining three achievements are "vuud" (beat Orakh without opening any small gates), "shpaara" (ride the elevator after the first fireball gate in Init), and "vivo" (disturb all three colonies of insects in Tulan). None of these achievements are reflected as progress in the hub or the savefile, only through Steam, and I would argue they ought to constitute a separate category.

TIMING AND ENDINGS

The any% normal ending timing stops the timer when the marble makes contact with the descending ball, and this occurs before the game saves normal ending completion to your savefile and awards the normal ending achievement. The saving of completion actually occurs when the save icon appears on screen, after the marble is absorbed by the white orb. The achievement is obtained during the scene with the expanding white orb, after the third cinematic "cut", in the shot where you can see the prickly things that you saw before you gained control in the levels. Exiting the game (e.g. with Alt+F4) before the save point will not save your ending and will keep all the normal levels locked, so this is the point at which the ending should be considered collected for 100% purposes.

The any% secret ending timing, by analogy, should stop the timer when the marble makes contact with the spinning floating pyramid, to mirror the normal ending timing. For the purposes of 100%, there is no visible savefile progress but the achievement is awarded during the cut to black, which happens less than a second after touching the pyramid.

ANY% SECRET ENDING

Completing the secret ending does not require the collection of 42/44 collectibles. The reason for this is that you can just barely activate the secret levels' entrances from the sides. As a result, the secret ending is competitive with the normal ending as far as any% is concerned, because you only need to complete up to level 9 before tackling the secret levels. For this reason I have placed secret ending as a subcategory under any%, and the previous definition of any% is now the other subcategory, any% normal ending.