I made this up when I was about ten, long before I had read The Lord of the Rings or heard about Esperanto, and for reasons I no longer remember (I think "because I could" is probably as close as you'll ever get). Nearly two decades have dimmed my memory of the details somewhat, but I can confidently say that there wasn't much more than this.
Not knowing any better, I began by assigning sound values to the consonants of the Roman alphabet. For reasons now lost to history, it was decreed that T and D were to be pronounced [s] and [z]; to get [t] and [d] you had to spell them PT and BD. I think that most other consonants were the same as in English; there may have been a [x] (as in "loch", being a Scot) in there somewhere.
Y having been declared a vowel, I assigned values to most of the 42
possibile combinations of one or two vowel letters. This is what I
remember; the word in quotes containes the vowel sound in
question. The choice of these sounds for these spellings should
be regarded as somewhat arbitrary.
In this language, the infinitives of most verbs were formed on the pattern CVVCVC (C=consonant, V=vowel). Thus teozik "to have", maaron "to be". (I don't remember any more.) The present tense was formed by taking these letters in various combinations according to the person and number: ek teo "I have", ? tozik "you have", yapt zok "it has", ? zoek "we have", ? tozik "you (pl) have", ?teozik "they have". Vowels not found in the verb stem could thus appear in the conjugation, which is why each combination of vowel letters had to have a pronunciation. (I was only ten, be fair.)
Past and future tenses (there weren't any more) were formed from the present tense by adding the appropriate particle, which was individual to the verb (OK, and completely arbitrary): ek teo za "I had", ek teo fu "I will have".
I got as far as a second conjugation of verbs (seven letters), and then stopped, not really having any need or use for my creation. In all fairness it was next to useless anyway. Nevertheless, I still wonder if any other language, real or invented, has ever had a verbal system anything like this one. Can anyone else enlighten me?
No I can't - I want to look at some proper conlangs.