Idoburgish

General information
Idoburgish is a Germanic language formerly spoken in an isolated village in western Germany. The name "Idoburg(ish)" doesn't come from the language itself, instead it comes from the contemporary adaptation of the village's name.

So, the speakers were migrants who were reportedly exiled and travelled to the area almost directly north of Aachen, Germany, on the border with the Dutch Limburg. The local languages (namely Limburgish and, to lesser extent, Dutch and Ripuarian) have influenced the language both grammatically and lexically, and several other languages (Old High German, Old Saxon, Old Dutch) contributed only (or mainly) to its vocabulary.


 * Historical sound changes
 * Features to implement later

Consonants
The Idoburgish consonant inventory is pretty conservative, with some innovations most of which have been introduced by the end of Proto-Idoburgish (i.e. by the time of tribes entering the central south of modern Germany).

Vowels
All short vowels except <ö> and <ë> (which is a semivowel which I put in this table because of absence of a corresponding approximant) distinguish nasality.

Long vowels distinguish tone based on their height: high vowels (i.e. higher than mid) get a falling tone and low vowels get a drag tone, which is noticeably weaker than the falling tone and is technically a weak rising tone.

If a tone is present on a short vowel, it's indicated with an acute or a grave for drag and falling tone respectively.

Nouns
Oh the endless declension classes and the declension conservativity... *disregards* I'll say I wanted it to be as irregular and messed up as humanly possible.

Most noun declensions are divided into 2 varieties: hard (non-changing) and soft (palatalizing; itself distinguishing initially non-palatalized and initially palatalized). A root's variety is detected in a really simple way - initially non-palatalized soft roots end in J, initially palatalized soft roots end in Jʲ and hard roots end in any other consonant (stems ending in are initially palatalized soft stems). The declension differences between these two are very subtle.

W-umlaut
The W-umlaut (marked +W) is a recent introduction, involving lengthening of root vowels in plurals (much like the umlaut in German). Because of its recent introduction, it's applied after any other umlaut, as in tur > *töri > tööri.

The effect of the W-umlaut is lengthening of short vowels (see the vowel table). affected by the W-umlaut acquire the semivowel <ë> after themselves.

The second W-umlaut (marked +WD) converts the V:ë sequences  and long vowels into long vowels and diphthongs respectively.

The third W-umlaut (marked +Wd) converts all diphthongs and long vowels resulting from the previous W-umlaut processes into short vowels.