I keep trying to create a minimal grammar that will allow for
arbitrarily complex sentences with as few rules as possible. Here's my
latest effort with 8 grammar rules:

A Bare Bones Grammar

1. The basic sentence is SV, where S may be a single noun/pronoun or a
phrase. V is always a single verb marked for tense, mood, and aspect.
S and V always appear in that order.
____"I am-running."
____"John laughed."
____"Mary would-have-smiled."

2. A basic sentence may be modified with one or more extenders, E,
which may appear before, between, or after the S and V. Examples

3. An extender may consist of:

__A. An adverb or adverbial phrase.
____Example: "John laughed [quietly]."
__B. A preposition or prepositional phrase.
____(Transitive verbs require a preposition of some kind
____on the direct object.)
______"John laughed [at the clown]."
______"John gave [to Mary] [OBJ the book]."
__C. An Adjective or adjectival phrase with a copula-like verb.
____Example: "John was [sad]."
__D. A complete sentence prefaced by a connector.
____A connector is a conjunction or any non-preposition that
____can join two complete sentences. This includes words like
____"if", "and", "before", "or", "while", "until", "that", etc.
______"I will-stay [AND Tom will-go]."
______"I will-go [IF it is-raining]."
______"I will-go [WHILE the sun is-shining]."
______"[UNTIL the rain stops] I will-stay [at home]."
______"I told [to Mary] [THAT John is-laughing]."

4. A noun may be preceeded by a single determiner, and/or quantifier,
and any number of adjectives or adjectival phrases. Possesive pronouns
act as adjectives in this context. A quantifier may be a single word
like "several" or a quantifying phrase like "three or four".
____"the dog"
____"several brown dogs"
____"three or four really ugly brown dogs"
____"my five brown dogs"

5. A noun may be followed by one qualifier phrase. A qualifier phrase
is "which" followed by a complete sentence with a pronoun that is
optionally dropped when it refers to the modified noun.
____"I saw the dog [which (he) chased the car]."
____"I saw the boy [which (he) ran away]." (English: "I saw the boy
who ran away.")
____"I saw the man [which (he) ran into the building [that (it) was-burning]]."
____"I found the boy [which I knew (he) had run away]."

6. A conjunction may join any two items which are syntactically
equivalent. In other words, a noun with another noun or noun phrase,
an adjective with an adjectival phrase, and so on. The resulting
compound is syntactically equivalent to its constituent parts.
____"[dogs AND cats](n)"
____"a [red AND blue](adj) balloon"
____"he [runs AND jumps](v)"
____"[over the river AND through the woods](prep-phrase)"
____"[John 's fourteen big red books](n)"

7. Interrogatives are formed by using an interrogative meta-adjective
where an adjective would normally be found, or by using an
interrogative meta-noun where a noun or pronoun would normally appear.
____"An apple is [what-color]?"
____"He gave the book to [what-person]?"
____"You will go to town at [what-time]?"

8. Yes or no questions are formed by appending "yes?", "no?",
"maybe?", "perhaps?", "I wonder", "eh?" etc. to a statement, or by
ending the statement with a question mark or questioning tone.
____"He went to town, eh?"
____"He took his bicycle, no?"
____"He will be back later perhaps?"
____"You will let me know?"

Some examples:

__I will-go. (SV)
__I will-go [to home]. (SVE)
__I will-go [to home] [tomorrow]. (SVEE)
__I will-go [to home] [after the game]. (SVEE)
__I will-go [to home] [if it rains]. (SVEE)
__I will-go [to home] [when you stop [that (you) are-nagging [at me]]]. (SVEE)
__I will-go [to home] [because I am-done [at here]]. (SVEE)
__I will-go [to home] [while you wait [at here]]. (SVEE)
__I will-go [to home] [before you can-stop [OBJ me]]. (SVEE) where
final E = "before SVE"
__[To home] I will-go. (ESV)
__[Tomorrow] I will-go [to home]. (ESVE)
__I [after the game] will-go [to home]. (SEVE)
__[If it rains] I will-go [to home]. (ESVE)
__[When you stop [that (you) are-nagging [at me]]] [to home] I will-go . (EESV)
__[Tomorrow] I [to home] [because I am-done [at here]] will-go. (ESEEV)

Sample translation:

English: It is reached through a huge, arched entrance on which I
observed strange, fantastic carvings, which threw queer shadows under
the light of my candle.

[...] is prepositional phrase (Rule 3b)
(which ...) is noun qualifier phrase (Rule 5)

It is-reached
__[through a huge, arched entrance
____(which I observed
______[upon it]
______[OBJ strange, fantastic carvings
________(which they threw
__________[OBJ queer shadows]
__________[under my candle 's light]

Let the OBJ marking preposition (particle) be "em", and the possesive
particle "'s" be "ez".

Translation: It is-reached through a huge, arched entrance which I
observed upon it em strange, fantastic carvings which they threw em
queer shadows under my candle ez light.

Any sentences that can't be adequately translated? Any rules that need
to be added? Any rules that can be streamlined?